Journal of the Neurologmal Sctences, 1977, 34 131-145

131

© Elsewer Soentzfic Pubhshlng Company, Amsterdam - Printed m The Netherlands

S A T E L L I T E CELLS A N D M U S C L E R E G E N E R A T I O N IN DISEASED H U M A N S K E L E T A L MUSCLES

SAMUEL M CHOU and IKUYA NONAKA* Departments of Neurology and Pathology ( Neuropathology), West Vtrgmta Umverstty Medwal Center, Morgantown, W Va 26506 ( U S ,4 )

(Received 29 Aprd, 1977)

SUMMARY By virtue of the lanthanum nitrate staining techmque applied to blopsled muscle we ale able to demonstrate interaction between satellite cells and parent myofibers, as well as development of premyocytes from activated satellite cells The process of regeneration in diseased muscle appears to differ from that described in experimental myogenesls Transformation of activated satellite cells to two types of premyocytes in the process of muscle regeneration seems to rely primarily on the state of lnnervatlon and recovery rate of the parent cell after injury Activated satellite cells are characterized morphologically by proliferation of caveolae, first on the parent fiber side, and early T-tubule and myofilament formation and central displacement In diseased human muscle the satellite cells appear to play significant roles in muscle regeneration both as a source of reinforcement for falling metabolism in the parent cell and as potential replacements for the necrotic segment of the parent cell This study also demonstrates that the satellite cells are capable of developing into independent myocytes which may fuse with or replace the parent cell, dependent upon the type and extent of the injury sustained Abnormal fusion among premyocytes or with their parent fiber, resulting in formation of split- or ring-fibers, becomes conceivable when both lnnervatlon and recovery from the injury of the parent cell are delayed Thus, myotube formation, characteristic of usual myogenesIs, seldom takes place in the regenerative process instituted by satellite cells in diseased human skeletal muscles

INTRODUCTION The satellite cell is a mononuclear cell enclosed within the basement membrane

* This study was done during the tenure of a Research Fellowship of Muscular Dystrophy Assocmtlons of America, Inc Supported in part by WVUM corporatmn grant

132 of a striated muscle fiber but separated from the sarcolemma of the same muscle tiber Since Mauro's first electron-microscopic description of satelhte cells (1961), the~ have been considered dormant myoblasts playing an important role m myogenesls (lshlkawa 1966), or in muscle regeneration following various inJuries (Price, Howes and Blumberg 1964, Shaflq and Goryckl 1965, Allbrook, Baker and Klrkaldy-Wflhs 1966, Church, Noronha and Allbrook 1966, Carlson 1973, Rezmk 1969 and 1973) About one third of the nuclei m muscles of newborn ammals are estimated to be of satelhte cells (Allbrook, Han and Hellmuth 1971) Satellite cells have thus been linked to the process of muscle regeneration, however, the evidence remains largely orcumstantlal Although the precise population of the satelhte cells has not been estimated, a general ~mpresslon has been gamed that satelhte cells appear to be increased m number m various d~seases of human skeletal muscles (Laguens 1963, Shafiq, Goryckl and Mllhorat 1967, Alolsi 1970, Cohen and Bell 1970, Mastagha, Papadlmltnou and Kakulas 1970. Nonaka, Muke, Ueno and Mlyoshlno 1973, Van Haelst 1970) A recent quantitative study on the satellite cells of biopsled muscle fibers from patients with Duchenne muscular dystrophy has indicated a significant increase in their number (Wakayama 1976) The majority of studies on muscle regeneration have been performed over relatwely short periods of time on experimental animals after focal muscle injuries Since human muscle d~seases tend to be more insidious m onset, mole chromc, and more widespread, the mode of human muscle regeneration may differ significantly from that described in experimental animals The present ultrastructural study attempts to assess the role ofsatelhte cells in normal and abnormal muscle regeneration in diseased human muscles, and to compare it with muscle regeneration previously described m various experimental studies MATERIALS AND METHODS Biopsy specimens were obtained from patients with various muscle diseases, including both childhood (5 cases) and adult (8 cases) polymyosltlS, muscular dystrophies (3 cases), glycogen storage disease (2 cases), Werdmg-Hoffmann disease (3 cases), amyotrophlc lateral sclerosis (2 cases), peripheral neuropathies (5 cases), vascuhtls (5 cases) and other neurogenic diseases (8 cases) Within 5 mm of open biopsy, muscle specimens were fixed m cacodylate-buffered glutaraldehyde solution at pH 7 3 for 20-30 rain For lanthanum nitrate staining, small segments not exceeding 1 mm m diameter were post-fixed with gentle agitation for 2 hr at room temperature m a medium containing 1 3 % osmium tetroxlde in 0 2 M s-colhdme buffer (pH 7 4) and 1 2 % lanthanum nitrate prepared according to the method of Revel and Karnovsky (1967) The tissues were quickly dehydrated in gl aded ethanol and embedded in E p o n Araldlte Ultrathm sections were cut with an LKB Ultrotome with glass knives, doubly stained with uranyl acetate and lead mtrate, and examined in an AEI (Corinth 275) electron microscope RESULTS Active muscle regeneration and Increased numbers of activated satellite cells

133

Fig l Clear demarcation, by La staining of the satellite cell (S) and transverse tubules (arrows) in the undamaged parent fiber (PF) Note caveolae along the apposlng membranes of the satelhte cell and the parent muscle fiber 17-year-old female with dermatomyosltls × 18,400 Ftg 2 Twin satelhte cells separated by the plasma membranes (arrows) probably formed after a recent division, 23-year-old male with undetermined type of myopathy x 18,800 are observed in virtually all of the diseased muscles examined, but are most notable in the specimens from acute polymyosltlS of younger age groups In the case of a 2-yearold boy with acute dermatomyosltlS, for example, approximately 35 ~o of nuclei belong to satellite cells and 65 ~ to muscle fibers, on random counting of 150 nuclei in different fields According to the recent quantitative studies, the mean percentage of satellite cell nuclei in the muscle fibers from a normal individual of 3 years of age is 8 59 ( W a k a y a m a 1976), and that of 7 years of age 4 9 ~ (Schmalbruch and Hellhammer 1976) In " n o r m a l " muscles the satellite cells are mononucleated and have scant cytoplasm containing small numbers of ribosomes, endoplasmlc retlculum, mltochondrla, Golgl complexes and plnocytotlc vesicles (Fig l) The latter are scattered randomly along the inner surfaces and less commonly along the outer surfaces of the satellite cells and open to the intercellular space between satellite and parent cell The satellite cell vesicles are structurally identIcal to the caveolae (Yamada 1955 Zamplghl, Vergara

134

Fig 3A An actwated satelhte cell containing abundant rough endoplasmlc retJculum, mbosomesand prominent centnole (arrow) 6-year-old boy with dermatomyosms 11,600 Fig 3B Filamentous and microtubular structures in the activated satelhte cell (S) 66-year-old male with diabetic neuropathy 33,000 Fig 3C Actlvatedsatelhtecell An mcreasednumberofcaveolaealongtheapposmgmembranes of the satelhte cell and parent myofiber Note the absence of caveolae along the outer surfaces of the satellite cell covered by the basement membrane, and a prominent nucleolus (Nn) 6-year-old boy with dermatomyos~tls 13,200 and R a m o n 1975) or mlcropmocytotlc veszcles seen along the sarcolemma of the parent myofibers (Odor 1956, Ashurst 1969) The caveolae of both satelhte and parent cells are readily stained with lanthanum mtrate Although we were unable to demonstrate satelhte cells m cell division, the presence of a centrlole m the cytoplasm (Fig 3A) and occasional twin satelhte cells separated by plasma membranes (Fig 2) are highly suggestwe that they are capable of mitotic dwlslon (Shafiq, Goryckl and Mauro 1968, Shafiq 1970, Allbrook et al 1971) Satelhte cells with a small number ofcaveolae along the inner cell surface but only a few or no caveolae along the sarcolemma of the parent cell (Figs 1 and 2) are beheved to be m the quiescent stage Even m muscle fibers which appear normal, the assocmted satelhte cells frequently &splay ultrastructural characteristics suggesting actwatlon, such as increased numbers of caveolae, ~rregularly shaped nucle~ with indentations of the nuclear membrane, prominent nucleoh, and increased numbers of organelles and occasional filamentous

135

Fig 4 Lanthanum mtrate penetrating into deep cytoplasm of an actwated satelhte cell (S) along coalesced caveolae in cactus-hke pattern of early T-tubule formation (arrows) Note disarray ofmyofibrils m the parent fiber (PF) 66-year-old male with neurogemc atrophy × 60,000

(7 nm) and mlcrotubular (24 nm) structures in the cytoplasm (Figs 3A and B) In a more activated stage, the caveolae are markedly increased in number along the inner surfaces of the apposlng plasma membranes of both satellite and parent cells, forming clusters and aggregates (Fig 3C) The caveolae are usually separated from each other, but in some areas a few or more seem to coalesce, forming cactus-like, primitive, tubular structures (Fig 4) The tubular structures appear to be continuous with both the satellite cell and parent myofiber with occasional formations of elaborate networks of transverse-tubules (honeycomb-like structures) or infolded membranes (Figs 5A and B) As shown in Fig 6A, the tubular structures branching and proliferating Into the deep cytoplasm of the satehte cells seem to represent early T-tubule formation, which appears to be essential for ultimate fusion with parent myofibers Along with active T-tubule formation, a tendency for activated satellite cells to move inward, or centralization, ~s noted Such a phenomenon of centrahzatlon is particularly c o m m o n for an activated satellite cell in a degenerating parent myofiber (Fig 6B) Such activated satellite cells eventually synthesize myofibrlls and seem to have at least two potential fates in the scheme of muscle regeneration The activated satellite cells which contain myofibrlls are termed "premyocytes" and 2 types have been recognized "Premyocyte type I"

136

Fig 5A Early T-tubule formation with comphcated honeycomb-hke structure (arrow) and infolded membranes along the borderhne between the activated satelhte cell and the parent muscle fiber Nucleus in the parent fiber (N) 61-year-oldfemale with neurogemc atrophy × 7,200 Fag 5B Similar findings as seen m A Lysosomesand hpofuscln granules (L) are occasionally seen m the activated satelhte cells especially m the aged group Note the corrugated nuclear outlines 64-year-old female with neurogemc atrophy × 23,400 designates a cell which has developed from an activated satelhte cell within a sarcolemmal tube, contains orderly myofibrlls which are parallel to those of the parent or surrounding fibers, and is ready for delayed fusion or for becoming an independent, innervated, and functional myocyte Such a premyocyte type I is shown in Fig 7 which displays orderly myofibrds consisting of both thick (17 nm) and thin (7 nm) myofilaments, as is seen in mature muscle fibers Premyocytes type I may continue to grow and replace the necrotlzed parent cell, or fuse with the parent cell which may have recovered from the antecedent injury More commonly such a premyocyte tends to fuse completely or partially with the sister premyocytes within the same sarcolemmal tube while macrophages are still scavenging the debris from the necrotlzed parent cell (Fig 8) Alternatively, the parent cell may become severely degenerated after satellite cell activation In other words, activated satellite cells may remain intact after the parent myofiber has undergone degeneration Such an activated satellite cell, deprived of any posslblhty of neural influence through the parent cell, is termed the "premyocyte type I I " It is characterized by (Fig 9) haphazardly arranged myofibrlls and conglomer-

137

Fig 6A An activated satellite cell embedded in the atrophic parent fiber with prominent T-tubule formation Early extension of T-tubules into the deep cytoplasm of the activated satellite cell (reset) Note a mildly actwated satelhte cell at the top 6-year-old boy with dermatomyosltls × 4,100 and w 10,200 Onset) Fig 6B Centrahzation of activated satelhte cell with active T-tubule formation (arrow) becoming a premyocyte type I, m a degenerating parent fiber 18-year-oldfemale with dermatomyosltis × 32,000 ated cytoplasmic processes with irregular myofilaments and Z-discs (arrows), but no actwe caveola or T-tubule formation along the apposmg membranes, except for the portion initially actwated In the event of total necrosis of the parent myofiber with preservation of its sarcolemmal tube (arrowheads, Fig 10), the actwated satelhte cell may become a premyocyte containing aimlessly arranged myofibrds, having no relat~onshlp to the longitudinal axis of surrounding muscle fibers These premyocytes are apparently non-functional, and may remain static unless innervated If the parent myofiber falls to recover from injury and undergoes necrosis, the premyocyte may be arrested within the empty sarcolemmal tube DISCUSSION There is httle doubt that the human skeletal muscle fiber is capable of regeneration after injuries (Walton and Adams 1956, Allbrook et al 1966, Sloper, Bateson, Hmdle

139

Fig 9 Haphazardly grown cytoplasmic processes of a premyocyte type I1 with all-formed Z-disks (arrows) and myofilaments, embedded within the degenerated parent fiber Note absence of caveolae along the most of apposmg membranes except for a segment m the upper l/3 where both early T-tubule and caveola formatmns are present Note also the extent of the degeneration m the parent fiber (inset) 18-year-old female with dermatomyositlS - 15,600 and ~ 1,950 (reset) a n d W a r r e n 1970, Baloh, Cancllla, K a l y a n a r a m a n , M u n s a t , Pearson a n d Rich 1972) I n various disease processes in muscle, b o t h n e u r o g e m c a n d myogenic, active regenerative p h e n o m e n a have been described, particularly in y o u n g e r patients (Pearson 1962, Laguens 1963, G d b e r t a n d H a z a r d 1965, Shafiq et al 1967, Van Haelst 1970, M a s t a g h a a n d K a k u l a s 1970, M a s t a g h a et al 1970, F r e u n d - M o l b e r t a n d Ketelsen 1973) F i n d i n g s of occasional myoblasts a n d m y o t u b e s at the periphery of muscle fibers have suggested that regeneration in h u m a n skeletal muscle is " d i s c o n t i n u o u s " or e m b r y o n a l in type (AlolSl 1970) I n the d i s c o n t i n u o u s type of regeneration, the m o n o -

Fig 7 Premyocyte type I (PI, in early centralization, enclosed m the common basement membrane and wrapped partly by sarcoplasm of the parent muscle fiber The premyocyte type I possesses orderly myofibrlls wtth both myosin and actm filaments (reset) and appears to have developed from one of the twin satelhte cells The other twin satellite cell (S) still appears qmescent Not stained with lanthanum mtrate 21/2-year-old with dermatomyosltlS × 6,300 and "< 41,000 (reset) Fig 8 Active muscle regeneratmn m the sarcolemmal tube containing phagocytes scavenging necrotic parent fiber (NF) surrounded by premyocytes I with early myofibrll formation (Inset) Not stained with lanthanum nitrate 13-year-old boy with dermatomyositls, × 4,800 and s 22,000 (Inset)

F

.

.

.

.

.

.

.

.

.

Fig 10 Premyocyte II possessing aimlessly arranged myofibrils and Z-disks (arrow) m the empty sarcolemmal tube (arrow heads) It ma~ be easll~ m~staken as a satellite cell of the neighboring myofiber (meet) 63-year-old male with neurogemc atrophy × 20,000 and × 2,400 (inset)

Per,0her%o,nos," I~l I |11111 _~I~Hil

DelayedRecovery I ~ l l l l | E 1 ~ [j[~.i~l[~.%id FastRecovery

~,'. ~ i i l

Act,re,onof 1~a l l ~ i

. . . . . .

Sotelhte Cells i r , , ' l i ~ l i l r / ~_ I ~ . ~ . /

/

,

- ~ ] ~ $

/

~E3m#

.~'~_~

Ili[~iill ~

~.-~.P_~..21~ lllfIT311

l0~Uii|!f Injuryt ~ ! l l l l ~ No Fus,on IBilil~m Porer~tF~ber ParentF,ber Necrotn:~ed:llll~.~Ml~

S.~'~'.~.",.,'~'~.%

I~INNERVATION,NTACT ,

"""'~L II~ '~~ i ~l l , ~

~ l

] ,"~|~ll~!~J~lll

cyte -[-

I

e

O~u~escr~e!!;ateIhte Cell

,n,or.a,

. . . . .

~;~llal Centrol~Nucleus

~

,,,, ~

~ ?

~Degen~rat,n'cj

Sotelhte CellsII-V ~1~l~tlI Prem(~oc~i' ~" R I I n j u r y @ n t Fiber [ WITH DENERVATION I

~ ~ i ,

S,ster Sotelhte Cells

ir;4~HIili ~ ~!1||1~

x FFa,lure us,on_of_ ,~, ~ , ~Denervohon'~l~ \\ l~"111ilHl,.

! Spht ~ o l lF,~ber y I

er o on

~

/'Fa,,ureo, IFC,l'9tl Re,nnervahonrh'~'.'JIt

/

,;llr~l~1~1~

,|,,..~IF

/

#

Dual / Remnervahon

/

/

/~l~,"~..".a~/

! ~.--'.~rliik

~1 Pre.yocyte~ / ~ ~ ~ ~'~ - ~1 Relnnervahon l ~ ~.n~i~' "~-~1~1 DelayedFus,onwdh ParentF,ber WR-e~e(~ ~1 FRecover,ng '~ae r RING FIBER

Fig 11 Diagram illustrating the role of satellite cells in normal and abnormal regeneration of muscle fibers

141 nucleated satelhte cells beneath the basement membrane presumably become the precursor myoblasts They may detatch from their parent cell and divide into numerous myoblasts, probably by mitosis (Gilbert and Hazard 1965, Conen and Bell 1970), before they fuse with each other to form multlnucleated myotubes or sarcoblasts (Price et al 1964, Reznlk 1973) Despite the general agreement that this type of regeneration takes place along the inner surface of the muscle fiber (sarcolemmal tube), there has been controversy as regards the origin of the mononucleated satellite cells lying between the basement membrane and sarcolemma of the parent fiber Four hypotheses have been advanced regarding the origin of satellite cells (l) they are dormant myoblasts which did not participate in the ortglnal myotube formation by the process of fusion of Individual myoblasts (Mauro 1961), (2) they are formed by reorganization of cytoplasmic membranes around the nuclei of striated muscle cells (Reznlk 1969, 1973), (3) they derive from the circulating hematogenous cells which migrate into the muscle (Sloper et al 1970), (4) they originate in the perlcytes of the blood vessels and merge into the muscle fibers if the regeneration is vast and intense (Freund-Molbert and Ketelsen 1973) Whatever the origin of the mononucleated cells beneath the basement membrane of the parent fiber, it is these cells which potentially contribute to the process of regeneration It is generally believed that satellite cells exist in greater numbers in developing myocytes or in muscle fibers after various injuries The stimulus for satelhte cell differentiation Is not known, but it has been thought to originate from the damaged fiber itself Teravalnen (1970) observed Increased numbers of satellite cells in the superior rectus muscle following compression injury so gentle as not to cause degeneration of the muscle fiber These satelhte cells appear morphologically different from those of normal muscle and are characterized by the presence of a conspicuous nucleolus and sparse pale cytoplasm containing a few small mltochondrla, granular endoplasmlc retlculum, and numbers of plnocytotlc vesicles along their cell membranes Satellite cells which possess such cytoarchltectural characteristics are highly suggestive of active development into myoblasts and have been designated as activated satellite cells (Shafiq 1970) or presumptive myoblasts (Reznlk 1970) Increased numbers of satellite cells have been observed in diseased human skeletal muscle, Including Duchenne muscular dystrophy (Laguens 1963, Shafiq et al 1967, Mastagha et al 1970, Wakayama 1976), myotonlc dystrophy (Alolsl 1970), congenital muscular dystrophy (Nonaka et al 1973), Werdnlg-Hoffmann disease (Van Haelst 1970), and polymyosltlS (Conen et al 1970) In the present study, the feature most characteristic and indicative of an early stage in the activation of satellite cells is the proliferation of caveolae along apposlng membranes of both the satellite and the parent cells as well as centralization of the satelhte cells In quiescent satelhte cells, only a few caveolae are seen, especially along the apposlng parent muscle cell membranes The caveolae are easily demonstrated by lanthanum nitrate staining In more advanced stages of activation they coalesce and fuse with each other, forming early T-tubules (cactus-like structure) along both satellite cells and muscle fibers These elaborate networks of T-tubules, although they have been described in various muscle diseases, seem to arise in a manner analogous to T-system formation observed during in vitro myogenesls (Ishikawa 1968)

142 During fusion of lndwldual myoblasts m myotube formation, the appearance ol vesicles and tubules has been described at the adjacent cytoplasm of the myoblast~ (Shlmada 1971, Lipton and Konlgsberg 1972) As soon as myotube formahon begmb m wtro, T-tubule prohferatlon starts, by mvagmatlon of the sarcolemma and subsequent extension by branching and budding (Ezerman and lshlkawa 1967, Lentz 1969) By analogy, active T-tubule formation in activated satelhte cells would strongly suggest that they are developing into myoblasts or premyocytes and that they are being prepared for fusion with the parent cell For such fusion, centralization of the activated satelhte cells may transiently take place lfthe recovery of the parent fiber from injuries is delayed, the centrahzed nuclei may remain within the fiber Although neither defimte cytoplasmic bridges nor fusion between satelhte cells and parent fibers were demonstrated m the present study, an increased number of caveolae, tubules, and membranous folds along the membranes not only of the satelhte cells but also of the parent muscle fibers would suggest eventual development of electrophyslologlc synchronlclty and ultimate fusion of both cells Alternatwely, this active tubule formation might be interpreted as the formation of "clefts" and "planes of cleavage" prior to separahon of satelhte cells from the parent myofiber as suggested by Rezmk (1973) However, such an active separation of a mononucleated cell from a diseased parent cell seems paradoxical Addmonally, some satelhte cells appear quite aged containing many lysosomal complex bodies or hpofuscm granules (Fig 5B) In growing muscle fibers of young ammals, the satelhte cells divide repeatedly and are incorporated into the parent myofibers (Moss and Leblond 1970, 1971 Allbrook et al 1971), thus contributing to the process of hypertrophy of the fibers (Reger and Crmg 1968) Slmdarly, in muscle recovering from injuries, the activated satelhte cells may incorporate into the convalescent parent myofibers Jf the latter are well innervated In experimental denervat~on, instead of incorporation into the parent myofibers, satelhte cells may become separate young muscle fibers, described as daughter fibers, enclosed in the common basement membrane of the fibers The satelhte cells are consldered to play a slgmficant role m the "fragmentation" of atrophic muscle on denervahon (Mlledl and Slater 1969) by sending their slender cytoplasmic processes into their denervated parent myofibers Thus, for fusion of activated satelhte cells to the parent myofiber the state of lnnervatlon of the latter seems crucml A tendency of the satelhte cells become independent from the degenerated parent fibers ~s suggested m Figs 7, 9 and 10 The presence of well-orgamzed myofibrlls wolates the definmon of the satelhte cell (Mmr 1970) yet other cytoarchltectural characteristics are in complete agreement with th~s definmon In fact, the presence of such d~stlnCtlVe myofibrds or sarcomeres m activated satelhte cells or premyocytes (Fig 7) has not been described m ordinary experimental or human muscles Recently, however, myofibrds have been described in satelhte cells of muscles in Duchenne muscular dystrophy (Wakayama 1976) Th~s would imply that the fusion of satellite cells with innervated parent myofibers "normally" proceeds rather qmckly, or production of myofibrlls does not occur m the qmescent satelhte cells The process of fusion may be delayed, either because the parent cell's recovery from inJuries or its remnervatlon was slow, or its disease process

143 progressed further Then, the activated satellite cell may grow independently from the parent myofiber and become a premyocyte of either type Development into either type of premyocyte and interaction of such premyocytes with the parent myofibers or sister premyocytes appear dependent upon the state of the lnnervatlon to that particular sarcolemmal tube, as summarized in the diagram (Fig l 1) The premyocyte type I may eventually become a matured myocyte within the basement membrane, replacing the necrotic parent myofiber ff lnnervatlon is preserved Instead, if lnnervatlon falls to occur after the parent cell has become necrotic, the activated satellite cell may remain as the premyocyte type II in an empty sarcolemmal tube (Fig 10) Conformity in the direction of myofibrlls and the development of elaborate tubular systems between the 2 or more premyocytes would result ultimately in fusion, provided 1 premyocyte is innervated It ~s conceivable that the premyocyte type I may acquire innervatlon from a motor unit other than that of the parent or from other premyocytes within the same sarcolemmal tube, and mature independently without complete fusion "Split-fibers" may thus be formed However, the conformity in the direction of myofibrlls does not always occur Occasionally the myofibrlls in the premyocytes type I are seen to be perpendicularly arranged to the myofibrlls of the parent cells In the event of delayed fusion of these 2 cells, the formation of ring fibers (Rlngblnden) may result "Sphttmg" or "longitudinal fiber division" of myofibers into daughter fibers was considered one of the most common features in muscular dystrophies (Adams, Denny-Brown and Pearson 1953) Electronmlcroscopyofsuchfibers(Hall-Craggs 1972) has demonstrated that among groups of small, recently separated fibers, occasional fibers showed evidence of degeneration By inference from the present study such a "degenerated fibel" among "recently-separated fibers" might be the degenerated parent myofiber The "recently-separated fibers"' might represent the premyocytes type I developed from activated satelhte cells These premyocytes may or may not fuse completely, in fact, formation of a typical myotube seldom occurs on fusion of premyocytes If fusion is incomplete, both the basement membrane and endomyslum may later extend into the clefts Thus, m a regenerative process of diseased muscle Involving satellite cells, two factors may affect the final outcome (1) the extent of lnjury or the rate of recovery from injury in the parent myofiber, and (2) the state of lnnervatlon of the parent myofiber, and, hence, the development of electrophyslologlcal synchromoty, which is an obvious prereqmslte for fusion of the satelhte cell to the parent cell It should be emphasized that when the satelhte cells are quiescent, the parent cells often appear healthy and seldom display any sign of active caveolae formation at the subsarcolemmal zone opposite the satellite cells The activation of satellite cells seems to be triggered or signaled first by the parent cells On the other hand, if the injury is intense and rapid, the parent cell may die before it activates the satellite cell, the latter would die concomitantly ACKNOWLEDGEMENT We thank Mr Gerald Voice for his techmcal assistance, Miss Gall Watson 1Ol her enthusiastic clerical help, and Dr T W Crosby for reviewing the manuscript

144 REFERENCES Adams, R D , D Denny-Brown and C M Pearson (1953) Dtseaws oJ M u s c l e - - A Stud~ tn Pathology, Harper and Row, l n c , New York, N Y , p 350 Allbrook, D B , W C Baker and W H K~rkaldy-Wllhs (1966) Muscle regeneration m experimental animals and in man, J Bone Jt Surg, 48B 153-169 Allbrook, D B , M F Han and S E Hellmuth (1971) Population of muscle satelhte ceils m relation to age and mitotic activity, Pathology, 3 233-243 AIolsJ, M (1970) Patterns of muscle regeneration In A Mauro, S A Shafiq and A T Mdhorat (Eds), Regeneratton oJ Striated Muscle, and Myogenests (Proceedings of the International Conference convened by the Muscular Dystrophy Associations of America, I n c , New York, 1969) (internat~onal Congress Series, No 218), Excerpta Medlca, Amsterdam, 1970, pp 180-19:~ Ashurst, D E (1969) The fine structure of pigeon breast muscle Ttssue Cell, 1 485-496 Baloh, R , P A Cancdla, K Kalyanaraman, T Munsat, C M Pearson and R Rich (1972) Regeneration of human muscle - - A morphologlc and hlstochemlcal study of normal and dystrophic muscle after Injury, Lab Invest, 26 319-328 Carlson, B M , 0973) The regeneration of skeletal muscle - - A review, Amer J Anat, 137 119 150 Church, J C T , R F X Noronha and D B Allbrook (1966) Satelhte cells and skeletal muscle regeneration, Brtt J Surg , 53 638-642 Conen, P E and C D Bell (1970) Study of satellite cells in mature and letal human muscle and rhabdomyosarcoma In A Mauro, S A Shafiq and A T Milhorat (Eds), Regenetanon o/ S m a t e d Muscle, and Mvogenest~ (Proceedings of the International Conference convened by the Muscular Dystrophy Associations of America, I n c , New York, 1969) (International Congress Series, No 218), Excerpta Medlca, Amsterdam, 1970, pp 194-211 Ezerman, E B and H Ishlkawa (1967) Differentiation of the sarcoplasmlc retlculum and T system m developing chick skeletal muscle in vitro, J Cell Btol, 35 405-420 Freund-Molbert, E and U - P Ketelsen (1973) The regeneration of the human striated muscle cell, Bettr path Anat, 148 35-54 Gdbert, R K and J B Hazard (1965) Regeneration m human skeletal muscle, J Path Ba~t, 89 503-512 Hall-Craggs, E C B (1972) The significance of longitudinal fiber dtv,slon m skeletal muscle, J neurol S e t , 15 27-33 Ishlkawa, H (1966) Electron microscopic observations of satellite cells with speoal reference to the development of mammalian skeletal muscles, Z Anat EntwwkI-Gesch, 125 43-63 Ishlkawa, H (1968) Formation of elaborate networks of T-system tubules in cultured muscle with special reference to the T-system formation, J Cell Btol, 38 51-66 Laguens, R (1963) Satelhte cells of skeletal muscle fibers m human progressive muscular dystrophy, Vtrchows Arch path Anat , 336 564-569 Lentz, T L , (1969) C2vtologlcal studies of muscle dedlfferentlatlon and differentiation during hmb regeneration of the Newt Tnturus, Amer J A n a t , 124 447-480 L~pton, B H and I R Komgsberg, (1972) A fine structural analysis of the fusion of myogemc cells, J Cell Btol, 53 348-364 Mastagha, F L and B A Kakulas (1970) A histological and hlstochemlcal study of skeletal muscle regeneration m polymyosms, J neurol Sct, 10 471-487 Mastagha, F L , J M Papadlm~tnou and B A Kakulas (1970) Regeneration of muscle in Duchenne muscular di~strophy - - An electron microscope study, J neurol Sct, 11 425-444 Mauro, A (1961) Satellite cell of skeletal muscle fibers, J btophys btochem Cvtol, 9 493-495 Moss, F P and C P Leblond (1970) Nature of dlwdlng nuclei in skeletal muscle of growing rats, J Cell Btol , 44 459-462 Moss, F P and C P Leblond ( 1971 ) Satellite cells as the sources of nuclei m muscles of growing rats. Anat Rec, 170 421-436 Mdedl, R and C R Slater (1969) Electron-microscopic structure of denervated skeletal muscle, Proc ro) Soe Lond, B174 253-269 Muir, A R (1970) The structure and dmtnbutlon of satelhte cells In A Mauro, S A Shafiq and A T Mdhorat (Eds), Regeneration o f Strtated Muscle, and Myogenests (Proceedings of the International Conference convened by the Muscular Dystrophy Assocmtlons of America, l n c . New York, 1969) (International Congress Series, No 218), Excerpta Medlca, Amsterdam, 1970, pp 91-t00

145 Nonaka, I , T Mnke, T Ueno and S Mlyoshmo (1973) An ultrastructural observation of satelhte cells m the blopsled muscles of congemtal muscular dystrophy, Brain Develop, 5 520-529 Odor, D L (1956) Uptake and transfer of particulate matter from the peritoneal cawty of the rat, J blophys btochem Cytol, 2 (Suppl) 105-108 Pearson, C M (1962) The regenerative capacity of dystrophic muscle after induced Injury In G H Bourne and M N Golarz (Eds), Muscular Dystrophy tit Man and Antmals, Hafner Publishing C o , New York, N Y , pp 16 Price, H M , E L Howes and J M Blumberg (1964) Ultrastructural alterations m skeletal muscle fibers mjured by cold, Part 2 (Cells of the sarcolemmal tube Observation on "discontinuous" regeneration and myofibrd formation), Lab Invest, 13 1279-1302 Reger, J F and A S Craig (1968) Studies on the fine structure of muscle fibers and associated satelhte cells m hypertrophic human deltoid muscle, Anat Rec, 162 483-500 Rewel, J P and M J Karnovsky (1967) Hexogonal array of subumts m mtracellular junctions of mouse heart and liver, J Cell Btol, 33 C7-C12 Rezmk, M (1969) Origin of myoblasts during skeletal muscle regeneration - - Electron microscopic observations, Lab lnve~t, 20 353-363 Rezmk, M (1973) Current concepts of skeletal muscle regeneration In S M Pearson and F K Mostofi (Eds), The Strtated Muscle, Williams and Wdkms C o , Baltimore, M d , pp 185-225 Schmalbruch, H and U Hellhammer (1976) The number of satellite cells m normal human muscle, Anat Re~ , 185 279 288 Shafiq, S A (1970) Satelhte cells and fiber nuclei in muscle regeneration In A Mauro, S A Shafiq and A T Mllhorat (Eds), Regeneranon o f Strtated Muscle, and Myogenests (Proceedings of the International Conference convened by the Muscular Dystrophy Assocmt~ons of America, I n c , New York, 1969) (International Congress Series, No 218), Excerpta Medlca, Amsterdam, 1970, pp 122 132 Shafiq, S A and M A Goryckl (1965) Regeneratlon m skeletal muscle of mouse - - Some electronmicroscope observations, J Path Bact, 90 123-127 Shafiq, S A , M A Goryckl and A T Mllhorat (1967) An electron microscopic study of regeneration and satelhte cells in human muscle, Neurology (Mlnneap), 17 567-608 Shafiq, S A , M A Goryckl and A Mauro (1968) Mxtos~s during postnatal growth m skeletal and cardiac muscles of the rat, J Anat (Lond), 103 135-141 Shlmada, Y (1971) Electron microscope observations on the fusion of ch~ck myoblasts m wtro, J Cell Btol, 48 128-142 Sloper, J C , R B Bateson, D Hmdle and J Warren (1970) Muscle regeneration in man and the mouse Evidence derived from tissue culture and from the evolution of experimental and surgical mjurtes m the irradiated and non-lrradmted subject In A Mauro, S A Shafiq and A T Mdhorat (Eds), Regeneratton o f Striated Muscle, and Myogenesls (Proceedings of the International Conference convened b2~ the Muscular Dystrophy Assocmtlons of America, I n c , New York, 1969) (International Congress Series, No 218), Excerpta Med~ca, Amsterdam, 1970, pp 157-166 Teravamen, H (1970) Satelhte cells of striated muscle after compression injury as shght as not to cause degeneration of the muscle fibers, Z ZellJorsch, 103 320-327 Van Haelst, U (1970)AnelectronmxcroscopmcstudyofmusclemWerdmg-Hoffmanndlsease, Vtrchows Arch path Anat , 351 291-305 Wakayama, Y (1976) Electron microscopic study on the satelhte cell in the muscle of Duchenne muscular dystrophy, J Neuropath exp Neurol , 35 532-540 Walton, J N and R D Adams (1956) The response of the normal, the denervated and the dystrophic muscle-cell to injury, J Path Bact, 72 273-298 Yamada, E (1955) The fine structure of the gall bladder eplthehum of the mouse, J btophvs btochem C)tol, 1 4 4 5 4 5 8 Zamplghl, G , J Vergara and F Ramon (1975) On the connection between the transverse tubules and the plasma membrane in frog semltendmosus skeletal muscle, J Cell Btol, 64 734-740 -

-

Satellite cells and muscle regeneration in diseased human skeletal muscles.

Journal of the Neurologmal Sctences, 1977, 34 131-145 131 © Elsewer Soentzfic Pubhshlng Company, Amsterdam - Printed m The Netherlands S A T E L L...
3MB Sizes 0 Downloads 0 Views