G.P.16.04 Ischemic central necrosis in pockets of transplanted myogenic cells in nonhuman primates: Implications for cell transplantation strategies
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Abstract Single myofibers with attached satellite cells isolated from adult rats were used to study the influence of the mature myofiber on the proliferation of satellite cells. The satellite cells remain quiescent when cultured in serum containing medium but proliferate when exposed to mitogen from an extract of crushed adult muscle. The response of satellite cells to mitogen was measured under three situations with respect to cell contact: (1) in contact with a viable myofiber and its basal lamina, (2) detached from the myofiber by centrifugal force and deposited on the substratum and (3) beneath the basal lamina of a Marcaine killed myofiber. The results show that satellite cells in contact with the plasmalemma of a viable myofiber have reduced mitogenic response. Since inhibiting growth may induce differentiation, I tested whether satellite cells proliferating on the surface of a myofiber would fuse. Although the satellite cell progeny were fusion competent, they did not fuse with the myofiber. To determine whether fusion competence of the myofiber changes with time in culture, embryonic myoblasts were challenged to fuse with myofibers that had been stripped of satellite cells and cultured for several days. The myoblasts fused with pseudopodia! sprouts growing from the ends of the myofiber, but did not fuse with the original myofiber surface. These results indicate that contact with the surface of a mature myofiber suppresses proliferation of myogenic cells but the cells do not fuse with the myofiber.
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Fuse (electrical)
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Single myofibers with attached satellite cells isolated from adult rats were used to study the influence of the mature myofiber on the proliferation of satellite cells. The satellite cells remain quiescent when cultured in serum containing medium but proliferate when exposed to mitogen from an extract of crushed adult muscle. The response of satellite cells to mitogen was measured under three situations with respect to cell contact: (1) in contact with a viable myofiber and its basal lamina, (2) detached from the myofiber by centrifugal force and deposited on the substratum and (3) beneath the basal lamina of a Marcaine killed myofiber. The results show that satellite cells in contact with the plasmalemma of a viable myofiber have reduced mitogenic response. Since inhibiting growth may induce differentiation, I tested whether satellite cells proliferating on the surface of a myofiber would fuse. Although the satellite cell progeny were fusion competent, they did not fuse with the myofiber. To determine whether fusion competence of the myofiber changes with time in culture, embryonic myoblasts were challenged to fuse with myofibers that had been stripped of satellite cells and cultured for several days. The myoblasts fused with pseudopodial sprouts growing from the ends of the myofiber, but did not fuse with the original myofiber surface. These results indicate that contact with the surface of a mature myofiber suppresses proliferation of myogenic cells but the cells do not fuse with the myofiber.
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Acute tubular necrosis
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Elutriation
Cardiac myocyte
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T-type Ca2+ channels (TTCCs) are expressed in the fetal heart and then disappear from ventricular myocytes after birth. The hypothesis examined in this study was the α1G TTCCs' influence in myocyte maturation and their rapid withdrawal from the cell cycle after birth.MethodsCardiac myocytes were isolated from neonatal and adult wild type (WT), α1G−/− and α1G over expressing (α1GDT) mice. Bromodeoxyuridine (BrdU) uptake, myocyte nucleation, cell cycle analysis, and T-type Ca2+ currents were measured.ResultsAll myocytes were mono-nucleated at birth and 35% of WT myocytes expressed functional TTCCs. Very few neonatal myocytes had functional TTCCs in α1G−/− hearts. By the end of the first week after birth no WT or α1G−/− had functional TTCCs. During the first week after birth about 25% of WT myocytes were BrdU+ and became bi-nucleated. Significantly fewer α1G−/− myocytes became bi-nucleated and fewer of these myocytes were BrdU+. Neonatal α1G−/− myocytes were also smaller than WT. Adult WT and α1G−/− hearts were similar in size, but α1G−/− myocytes were smaller and a greater % were mono-nucleated. α1G over expressing hearts were smaller than WT but their myocytes were larger.ConclusionsThe studies performed show that loss of functional TTCCs is associated with bi-nucleation and myocyte withdrawal from the cell cycle. Loss of α1G TTCCs slowed the transition from mono- to bi-nucleation and resulted in an adult heart with a greater number of small cardiac myocytes. These results suggest that TTCCs are involved in the regulation of myocyte size and the exit of myocytes from the cell cycle during the first week after birth.
Cardiac myocyte
Bromodeoxyuridine
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Magnetic resonance angiography
Peripheral vessels
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ObjectiveTo study the morphology of apopt osis of malignant tumors and its differences from necrosis.MethodsCancer tissues from 50 cases of various common cancers were measured by HE and in situ end labeling(ISEL) according to Gavrieli's metho d;positive and negative controls were made.3 cases were measured by M 30 -C ytodeath monoclone antibody immunohistochemistry.Apoptosis or necrosis lesions w ere divided into single cell,small piece,and massive according to the size.The a poptosis lesions(ISEL+) were divided into early,middle and late stage(the latter equal to apoptotic necrosis) according to the morphology.The criteria of non-a poptotic necrosis(necrosis) were ISEL(-),and no piknosis or karyorrhexis in HE. R esultsThe number of apoptosis lesion was signifieantly more than necro sis( P 0.01),while there were no evident differences among different sizes and among different stages of the apoptosis lesions( P 0.05).The apoptosis morphology was described.3 Cases of ovarian carcinoma were M 30 -Cytodeath positive i n the cytoplasm of apoptotic cance cells.The minor apoptotic necrosis lesions wa s special.There was no difference between apoptotic necrosis and necrosis in HE, while ISEL revealed positive nuclei.ConclusionThe majority of cancer tissues the HE morphology betwe en apoptosis and necrosis was evidently different,and ISEL was positive in apopt osis,negative in necrosis.So,both lesions were distinguishable.Although the mech anism of apoptotic necrosis was complicated,its ISEL was positive,so its nature should belong to apoptosis,not necrosis.In cancer tissues,the number of apoptosi s lesions was much nore than that of necrosis.
Karyorrhexis
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A major restriction of the intramuscular transplantation of myoblasts is that the grafted cells fuse mostly with myofibers along the injection trajectories. This has been attributed to a "lack of migration ability" of the grafted myoblasts. It has been assumed that grafted myoblasts remain motionless in the sites of delivery and fuse only with myofibers with which they come into contact. In the present study, we analyzed this phenomenon in 17 cynomolgus monkeys. We found that intramuscularly injected myoblasts within 1 hour after their injection are mainly located in the perimysium and not distributed along the injection trajectories. This suggested that the grafted myoblasts later migrate from the perimysium to fuse with myofibers that are damaged by the injections. Therefore, we analyzed whether β-galactosidase-labeled myoblasts injected subcutaneously over skeletal muscles migrate in needle-damaged and nondamaged muscle regions. We observed that grafted myoblasts migrated up to 1cm in depth from the muscle surface into the muscles, although they seemingly fused mainly with damaged myofibers. Our findings suggest that myoblast transplantation is not necessarily restricted bya "lack of migration ability" of the grafted cells but by the fact that myoblasts fuse with regenerating myofibers and not with undamaged myofibers.
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Morphology Study of the Junction between Cocultured Skeletal Myoblasts and Cardiac Myocytes in vitro
Objective:To investigate the morphological evidence for the connection of cocultured myoblasts and myocytes. Methods: Rat myocytes and skeletal myoblasts were cocultured with the ratio of 4:1. Cadherin,Connexin43 and NCAM were stained by ABC-AEC staining on day 2,4,7 and 14 respectively. The staining results were observed under microscope. Cells were compare d by transmission electroscope on day 4,7,10 and 14. Three groups were set as followed: experiment group (myocyte and myoblast were co-cultured with ratio 4:1), control group 1 (myoblast was cultured alone with same cell account), and control group 2 (myocyte was cultured alone with same cell account). Cells were digested and gathered on day 2,4,7,14 after cultured and RT-PCR was applied. Results were compared among the 3 groups. Results: Connexin43 was expressed in mypblasts and increased with cultural duration among the cocultured myoblasts and myocytes. The expression of cadherin also increased with the prolongation of co-culture time but less significant than that of connexin43. The expression of NCAM remained low until two weeks after co-culture. Connection similar to gap junction was observed to exist between myoblasts and myocytes under transmission electroscope. Conclusion: The myoblasts myocytelized in some characters after cocultured with myocytes: the fusion and maturation was delayed, the expression of connexin43 was increased Material bases and possibility for the connection similar to gap junction do exist among the co-cultured skeletal myoblast and cardiac myocytes.
Cardiac myocyte
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