Biological and morphological characterization of in vitro expanded human muscle-derived stem cells.

Stem cells are generally characterised as clonogenic and undifferentiated cells with the capacity of self-renewal and plasticity. Over the past few years, the adult stem cells have been derived from various types of tissues including the skeletal muscle. The main goal of the present study was the isolation, in vitro expansion and characterisation of muscle-derived stem cells (MDSCs). Thereby obtained results showed that MDSCs have a fibroblast-like shape with a large nucleus having one to four nucleoli. The cytoplasm was transparent without any signs of vacuolisation. TEM analysis showed an ultrastructure of cells with high proteosynthetic activity. MDSCs had a large and irregular nucleus with variable number of nucleoli. The cytoplasm contained a richly developed and rough endoplasmic reticulum, prominent Golgi apparatus cisterns as well as transport vesicles containing glycogen granules and variable microvilli and filopodia. They expressed alpha-actin and desmin. Results of the phenotypic characterization showed that the analyzed cells were positive for CD29, CD34, CD44, CD90, CD105 and HLA Class I. They did not express CD14, CD45, CD235a, HLA Class II and human fibroblast surface protein. According to these results it should be emphasised that MDSCs after performing the detailed studies focused on their immunological properties and differentiation potential may be used in the cell therapy of many degenerative diseases.