Interleukin-6 Type Cytokines On Adult Myoblast Proliferation And Differentiation Of Experimental Studies

The superfamily of interleukin-6-type cytokines regulate the proliferation, differentialtion, survival and apoptosis of cells, and play an important role in the procedures of anti-inflammation, hematopoisis, neuronal differentiation, and so on. Interleukin-6 (IL-6), leukemia inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) are the most important cytokines among this superfamily. Many investigations have been carried out broadly about the functions of these three cytokines on the hematopoietic and neural system, however, the effects on the proliferation and differentiation of adult human myoblasts have not been reported. As a type of cell population, myoblasts can provide the sufficient cell source, which will benefit not only the muscular atrophy, but also the central nervous system neurodegenerative diseases such as Parkinson's disease (PD). Because these cells can be abtained from the patients per-se, they possess the great clinical utility value.Our previous studies had demonstrated that CNTF with certain concentration inhibited the myoblasts to differentiate into mature myotubes. Therefore, in present study, we treated the myoblasts derived from the adult human skeletal muscles with different doses of IL-6, LIF and CNTF. The different effects of these three cytokines on the proliferation and differentiation of myoblasts were analyzed and compared. The functional mechanisms were also discussed, in order to confirm that these cytokines might be a new type of regulatory factors on the proliferation and differentiation of myoblasts. At the same time, adult human myoblasts were transplanted into the rat brain to verify the possibility of these cells as the therapeutic candidate on the neurodegenerative diseases of central nervous system.1. Proliferation, passage, freezing and refreezing of primary cultured adult human myoblastsThe myoblasts derived from the adult human skeletal muscles were cloned and all these cloned cells expressed the myoblasts-specific protein-desmin.2. The effects of IL-6, LIF and CNTF on the proliferation of myoblasts10 ng/ml LIF promoted the proliferation of myoblasts.3. The effects of IL-6, LIF and CNTF on the differentiation of myoblasts10 ng/ml LIF, 50 ng/ml LIF, 10 ng/ml CNTF and 50 ng/ml CNTF inhibited the myoblasts to differentiate into the myotubes, and inhibited the expressions of the myoblast differentiation-specific marker proteins-myosin and myogenin. Western result confirmed that LIF and CNTF inhibited the expressions of transcription factors-MyoD and Myf5, which regulated the maturation and differentiation of myoblasts.4. Survival, migration and differentiation of myoblasts after intracerebral transplantationAfter intrastriatal transplantation, adult human myoblasts could survive, but the survival rate was very low and differentiation capacity was not high. These cells could not form the neurons and glial cells, while maintained their myoblast property expressing the myoblast marker-MyoD.Conclusion: our results have shown that the effects of IL-6, LIF and CNTF on the proliferation and differentiation of adult human myoblasts were different. LIF in the dose of 10 ng/ml could accelerate the cell proliferation. LIF in the dose of 10 or 50 ng/ml and CNTF in the dose of 10 or 50 ng/ml could inhibit the myoblast differentiation. The inhibition mechanism might be that LIF and CNTF inhibited the expressions of transcription factor MyoD/Myf5 which could regulate the myoblast differentiation. In the experiment of myoblasts intracerebral transplantation, myoblasts without pre-induction in vitro could not differentiate into the neural cells. This result indicated that myoblasts may be in lack of the ability of multi-differentiation. This study will provide theexperimental and theoretic foundations for the basic and clinical researches of human myoblasts.