OBJECTIVE: To investigate the biological characteristics of human muscle satellite cell cultured in vitro. METHODS: Human muscle satellite cells were obtained from skeletal muscle biopsies of six patients during corrective orthopedic surgery, cultivated in growth medium for ten days, then in differentiation medium for additional five days. Human satellite cells were identified with monoclonal antibody against desmin. Cells were observed under phase contrast microscopy. RESULTS: Human muscle satellite cells proliferated in growth medium, and fused to form myotubes in differentiation medium. After 24 hours in differentiation medium, the confluent satellite cells began to fuse actively and achieved the top level at 72 hours. CONCLUSION: Human muscle satellite cell can proliferate and differentiate in appropriate culture condition. Immunocytochemical detection of desmin is the effective early method to determine satellite cell.
Objective
To analyze the glucolipotoxicity effects of glucose combined with free fatty acid (FFA) on ketone production and ultrastructure of skeletal muscle, by exogenous elevating circulating glucose and FFA concentration.
Methods
Fifty Wistar rats were divided into high-fat-feed induced obesity group (OB group, n=40) and ordinary feed as normal control group (NC group, n=10). Circulating glucose and FFA levels were increased by infusion in high-fat-fed obese rats. The levels of serum lipid, plasma FFA and beta-hydroxybutyric acid were detected by the horizontal colorimetry, and the microstructure of skeletal muscle was observed by transmission electron microscopy, especially the changes of the mitochondrial structure. Euglycemic-hyperinsulinemic clamp with tracer infusion was performed to assess peripheral insulin sensitivity.
Results
The average weight and body fat ratio in the OB group was higher than that in the NC group (P<0.05). Insulin clamp test to assess peripheral insulin sensitivity showed that the steady-state glucose Infusion rate in the OB group during clamp test was significantly lower than that in the NC group [OB: (19.26±1.84) mg/(kg·min)vs. NC: (28.82±1.69) mg/(kg·min), P<0.05]. The mitochondrial denaturation of skeletal muscle in the OB group of rats was observed, and the swelling and crest permutation, the accumulation of lipid droplets and cavitation were formed, and hypertrophy of mitochondria were also seen after intralipid and glucose infusion, which was obvious in the combined infusion group.
Conclusions
By exogenous elevating circulating glucose and FFA concentration, the products of ketone body increases. The mitochondrial damage of skeletal muscle suggests that mitochondrial may be the potential target of glucoxicity and lipotocicity.
Objective To reveal morphologic features and physiological function in compartments of human forearm muscles, and investigate the possibil ity of transplantation of neuromuscular compartments. Methods Sihler’ s neural staining technique was used to study the nerve branches distribution of forearm skeletal muscles in 5 human cadavers (aging26-39 years), including flexor carpi radial is, flexor carpi ulnaris (FCU), extensor carpi radial is brevis, extensor carpi ulnaris, palmaris longus (PL), flexor poll icis longus, pronator teres (PT). According to Wickiewicz’s methods, Ulnar compartment and radial compartment of forearm skeletal muscles above mentioned from 10 human cadvers were used to study the muscle architectural features. Results Each nerve branches run into the ulnar compartment and radial compartment respectively. There was statistically significant difference between the two physiological cross section areas (PSCA) of each neuromuscular compartment from forearm muscles(P lt; 0.05). Among them, PSCA of ulnar compartment of FCU was the largest. The PSCA of ulnar compartment of PT was the smallest. There was no statistically difference between the ratio (PSCA/muscle wet weight) of each neuromuscular compartment from forearm muscles (P gt; 0.05). As the ratio of PSCA to the muscle fiber length, the ulnar compartment of PT and the two compartments of PL had the highest one while the ulnar compartment of FCU had the smallest; and there was no statistically difference among the other neuromuscular compartments (P gt; 0.05). Conclusion Each of forearm muscles be divided into ulnar compartment and radial compartment and they have their own nerve supply. And there are significant differences in the physiological function in compartments of forearm muscles, which can be references in muscular compartment transplantation.
Objective To investigate the effect of various concentration of platelet-rich plasma (PRP) on osteogenic differentiation of rabbit skeletal muscle-derived stem cells (SMSCs) cultured in vitro. Methods Blood drawn from the central ear arteries of 9 one-year-old New Zealand white rabbits weighing 2.5-3.0 kg (male and female) was used to prepare PRP (Landesberg method). Full blood count and platelet count in PRP were tested. Soleus muscle of right hindl imb in rabbit was obtained and used to culture SMSCs in vitro. The cells at passage 3 were randomly divided into different groups: the experimental groups in which the cells were treated by conditioned culture media with various concentrations of autologousPRP (6.25%, 12.50%, 25.00%, 50.00%), and the control group in which the cells were treated with the media without PRP. At different time points after intervention, osteogenetic activity of the cells was detected by ALP staining observation, ALP activity detection was conducted, al izarin red staining for calcium nodules and immunofluorescence staining for osteocalcin were performed, and core binding factor α1 (Cbfα1) of osteogenic gene expression was tested by RT-PCR. Results The full blood PRP count and the platelet count in PRP was (3.06 ± 0.46) × 105/μL and (18.08 ± 2.10) × 105/μL, respectively. ALP staining: the cells in all the experimental groups were positive for the staining with many black sediment particles in cytoplasm; the cells in the control group were negative staining. ALP activity: all the experimental groups were higher than the control group (P lt; 0.05), the experimental group at 12.50% was superior to other experimental groups at each time point (P lt; 0.05). Al izarin red staining: at 14 days after culture, orange-red calcium nodules were evident in all the experimental groups; no orange-red calcium nodules were observed in the control group with a mineral ization rate of zero; there were significant difference between the experimental groups and the control group in terms of mineral ization rate (P lt; 0.05), the experimental group at 12.50% had a higher mineral ization rate than other experimental groups (P lt; 0.05). Immunofluorescence staining for osteocalcin: at 7 days after culture, the experimental groups were positive for the staining with yellow fluorescence in cytoplasm, and the result of the control group was negative. RT-PCR detection: no obvious changes of the gene expression were noted at 4, 12, and 24 hoursafter culture in the control group; the gene expression in all the experimental groups was significant superior to that of control group, especially at 12 hours, and the expression in the experimental group at 12.50% was the highest. Conclusion PRP can obviously promote the osteogenic differentiation of SMSCs cultured in vitro in a concentration-dependent manner, and the 12.50% is proved to be the ideal concentration.
OBJECTIVE To observe the ultrastructural changes and number of satellite cells in different muscles with different denervation interval and investigate the mechanism of denervation atrophy. METHODS Muscles of different denervation interval were harvested, which were 6 biceps brachii and 6 abductor digiti minimi. The ultrastructure of the samples were observed under transmission electron microscope. The number of nucleus and satellite cells were counted to calculate the percentage content of satellite cells. RESULTS In early stage of denervation, the myofilament and sarcomere of the majority were well oriented. The nucleoli of some muscle cell nucleus were enlarged and pale. Vacuolarization was also seen in some mitochondria. There was no obvious proliferation of collagen fiber around myofibers. After denervation of half a year, rupture and disorientation of myofilament was seen. The nucleus became smaller, dark stained, and some of them were condensed. There was proliferation of fibroblasts, adipose cells and collagen fibers around myofibers. Motor endplate was not recognized one year after denervation. In the early stage of denervation, satellite cell percentage of the two muscles was relatively high. It then declined with time. One year after denervation, satellite cells were scarcely detected. Comparison of the curves for satellite cell declination in two muscles revealed that the declination of the abductor digiti minimi was faster than that of biceps brachii. Decrease of the former started 3 months after denervation, while the latter started after 6 months. CONCLUSION Disappearing of motor endplate and proliferation of collagen fibers are main factors that affect the treatment outcome in late cases. Decrease of satellite cell number is another cause. The correlation of less satellite cell in abductor digiti minimi and poorer recovery of hand intrinsic muscles indicates that increment of satellite cells in long-term denervated muscles may be one of the effective measures to improve treatment outcome.
Objective To explore the effect of tri pterygium glycoside (TG) on the skeletal muscle atrophy and apoptosis after nerve allograft. Methods Twenty Wistar male rats were adopted as donors, weighing 200-250 g, and the sciatic nerves were harvested. Fifty SD male rats were adopted as recipients, weighing 200-250 g. Fifty SD rats were made the models of10 mm right sciatic nerve defect randomly divided into five groups (n=10): group A, group B, group C, group D and group E.groups A and B received fresh nerve allograft, groups C and D received sciatic nerve allograft pretreated with TG, and group E received autograft. The SD rats were given medicine for 5 weeks from the second day after the transplantation: groups A and E were given physiological sal ine, groups B and D TG 5 mg/ (kg·d), and group C TG 2.5 mg/ (kg·d). At 3 and 6 weeks, respectively, after nerve transplantation, general observation was performed; the structure of skeletal muscles was observed by HE staining; the diameter of skeletal muscles was analyzed with Image-Pro Plus v5.2; the ultrastructure of skeletal muscles was observed by TEM; the expressions of Bax and Bcl-2 were detected by immunohistochemical staining; and the apoptosis of skeletal muscles was detected by TUNEL. Results All rats survived to the end of the experiment. In general observation, the skeletal muscles of SD rates atrophied to different degrees 3 weeks after operation. The muscular atrophy in group A was more serious at 6 weeks, and that in the other groups improved. The wet weight, fiber diameter and expression of Bcl-2 in group A were significantly lower than those in groups B, C, D and E (P lt; 0.01)；those in groups B, C and D were lower than those in group E (P lt; 0.05); and there were no significant differences among groups B, C and D (P gt; 0.05). The apoptosis index and expression of Bax in group A were significantly higher than those in groups B, C, D and E (P lt; 0.01)；those in groups B, C and D were higher than in groupE (Plt; 0.05); and there were no significant differences among groups B, C and D (P gt; 0.05). Three weeks after nerve allograft, under the l ight microscope, the muscle fibers became thin; under the TEM, the sarcoplasmic reticulum was expanded. Six weeks after nerve allograft, under the l ight microscope, the gap of the muscle fibers in group A was found to broaden and connective tissue hyperplasia occurred obviously; under the TEM, sarcomere damage, serious silk dissolution and fragmentary Z l ines were seen in group A, but the myofibrils were arranged tidily in the other groups, and the l ight band, dark band and sarcomere were clear. Conclusion TG can decrease the skeletal muscle atrophy and apoptosis after nerve allograft. The donor’s nerve that is pretreated with TG can reduce the dosage of immunosuppressant for the recipient after allograft.
In order to explore the effects of clenbuterol on intramuscular collagen metabolism in denervated skeletal muscles, a randomized, double-masked and placebo-controlled group were studied. Seventy-one patients with complete function loss in muscularcutaneous nerve resulted from brachial plexus injury were administered clenbuterol or placebo 60 micrograms Bid for more than 3 months. Biopsies of the biceps brachia muscle were performed at the beginning and end of this study. The biopsied muscles were processed with anti-collagen I and IV immunohistochemical stains and image analysis as well. The result showed that the collagen proliferation of both type I and IV was much reducible in the clenbuterol-treated group than that of the placebo-treated group (P lt; 0.05). It was concluded that clenbuterol could inhibit partially the proliferation of intramuscular collagens in denervated skeletal muscle.
Objective To investigate an optimal method for SD rat skeletal muscle decellularization. Methods Sixteen SD rats (male and female) weighing 180-200 g were used. Thirty-six skeletal muscle bundles obtained from 10 rats were randomly divided into 3 groups: normal group (group A, n=4) received non-decellularization; time group (group T, n=16) andconcentration group (group C, n=16) underwent decellularization using hypotonic-detergent method. Concentration of sodium dodecyl sulfate (SDS) was 1.0% for T group, which was subdivided into groups T1, T2, T3 and T4 (n=4 per subgroup) according to different processing durations (24, 48, 72 and 96 hours). Group C was treated for 48 hours and subdivided into groups C1, C2, C3 and C4 (n=4 per subgroup) according to different SDS concentrations (0.5%, 1.0%, 1.5% and 2.0%). The muscle bundles of each group underwent HE staining observation and hydroxyproline content detection in order to get the optimal decellularization condition. Seven of 14 complete skeletal muscle bundles obtained from 6 SD rats were treated with the optimal decellularization condition (experimental group), and the rest 7 muscle bundles served as normal control (control group). The muscle bundles of each group were evaluated with gross observation, Masson staining and biomechanical test. Results HE staining: there was no significant difference between groups T1, T2, C1, C2 and C3 and group A in terms of muscle fiber; portion of muscle fibers in group C4 were removed; muscle fibers in group T3 were fully removed with a complete basement membrane structure; muscle fibers of group T4 were fully removed, and the structure of basement membrane was partly damaged. Hydroxyprol ine content detection: there was no significant difference between group A and groups C1, C2, C3, T1 and T2 (P gt; 0.05); significant difference was evident between group A and groups C4, T3 and T4 (P lt; 0.05); the difference between group C4 and groups T3and T4 was significant (P lt; 0.05); no significant difference was evident between group T3 and group T4 (P gt; 0.05). The optimal decellularization condition was 4 , 1.0% SDS and 72 hours according to the results of HE staining and hydroxyproline content detection. Gross observation: the muscle bundles of the experimental group were pall id, half-transparent and fluffier comparing with the control group. Masson staining observation: the collagen fibers of the experimental group had a good continuity, and were fluffier comparing with control group. Biomechanics test: the maximum breaking load of the experimental group and the control group was (1.38 ± 0.35) N and (1.98 ± 0.77) N, respectively; the maximum extension displacement of the experimental group and the control group was (3.19 ± 3.23) mm and (3.56 ± 2.17) mm, respectively; there were no significant differences between two groups (P gt; 0.05). Conclusion Acellular matrix with intact ECM and complete removal of muscle fibers can be obtained by oscillatory treatment of rat skeletal muscle at 4℃ with 1% SDS for 72 hours.
Objective To study the effect of motor nerve implantation after ectopic transplantation of skeletal muscle on nerve regeneration in rat. Methods Sixty Sprague-Dewley male 8 monthold rats were randomly divided into 3 groups: control group,in situ implantation group and ectopic transplantation group. In control group, obturator nerve controlling right gracilis was cut off. In in situ implantation group, the right gracilis was cut off and replanted to its original site, and the obturator nerve was implanted to the muscle. In ectopic transplantation group, the right gracilis was cut off and transplanted to the muscle of the left leg, and the obturator nerve was implanted to the muscle. After 25 weeks, the neurophysiological information was collected through electromyography and the weight of the muscle was measured. Results The potentialwithout control of the nerve existed in control group. There were no significant differences in latency, amplitude and conduct velocity betweenin situ implantation group and ectopic transplantation group(Pgt;0.05).The atrophy of gracilis was dominant incontrol group, the weight of the muscle was 158.0±19.3 mg. The weights of the muscle were 509.6±14.5 mg in ectopic transplantation group and 516.8±12.7 mg in in situ mplantation group, showing no significant difference (P＞0.05). The weights of the muscle in in situ implantation and ectopic transplantation group were larger than that in control group, showing significant difference(P＜0.05). Conclusion Motor nerve implantation after ectopic transplantation of skeletal muscle could prevent the atrophy of the muscle and resume partial function of nerve.
Objective To explore the in vitrodifferentiation of the rat mesenchymal stem cells (MSCs ) into the skeletal muscle cells induced by the myoblast differentiation factor (MyoD) and 5-azacytidine. Methods The MSCs were taken from the rat bone marrow and the suspension of MSCs was made and cultured in the homeothermia incubator which contained 5% CO2at 37℃. The cells were observed under the inverted phase contrast microscope daily. The cells spreading all the bottom of the culture bottle were defined as onepassage. The differentiation of the 3rd passage of MSCs was induced by the combination of 5-azacytidine, MyoD, transforming growth factor β1, and the insulin like growth factor 1. Nine days after the induction, the induced MSCs were collected, which were analyzed with the MTT chromatometry, theflow cytometry, and the immunohistochemistry. Results The primarily cultured MSCs grew as a colony on the walls of the culture bottle; after the culture for 5-7 days, the cells were shaped like the fibroblasts, the big flat polygonal cells, the medium sized polygonal cells, and the small triangle cells; after the culture for 12 days, the cells were found to be fused, spreadingall over the bottle bottom, but MSCs were unchanged too much in shape. After the induction by 5-azacytidine, some of the cells died, and the cells grew slowly. However, after the culture for 7 days, the cells grew remarkably, the cell volume increased gradually in a form of ellipse, fusiform or irregularity. After theculture for 14 days, the proliferated fusiform cells began to increase in a great amount. After the culture for 18-22 days, the myotubes increased in number and volume, with the nucleus increased in number, and the newly formed myotubes and the fusiform myoblst grew parallelly and separately. The immunohistochemistry for MSCs revealed that CD44 was positive in reaction, with the cytoplasm ina form of brown granules. And the nucleus had an obvious border，and CD34 was negative. The induced MSCs were found to be positive for desmin and specific myoglobulin of the skeletal muscle. The flow cytometry showed that most of the MSCs and the induced MSCs were in the stages of G0/G1，accounting for 79.4％ and 62.9％，respectively; however, the cells in the stages of G2/S accounted for 20.6％ and 36.1％. The growth curve was drawn based on MTT，which showed that MSCs weregreater in the growth speed than the induced MSCs. The two kinds of cells did not reach the platform stage，having a tendency to continuously proliferate.ConclusionIn vitro,the rat MSCs can be differentiated into the skeletal muscle cells with an induction by MyoD and 5-azacytidine, with a positive reaction for the desmin and the myoglobulin of the skeletal muscle. After the induction, the proliferation stage of MSCs can be increased, with a higher degree of the differentiation into the skeletal muscle.
