The skin may also contain large numbers of pluripotent cells. The skin contains various structures such as the epidermis layer, the dermis layer and the appendage, and has a large surface area and abundant cell resources. Moreover, the skin is superficial and easy to take. Recent studies have shown that cells with multipotential differentiation potential also exist in the dermis. After induction, neonatal rat dermal cells can not only differentiate into a variety of mesodermal cells, but also differentiate into endoderm cells such as islet cells under specific conditions. Mesenchymal-derived DP cells are obtained from the dermal papilla (DP) structure of adult rodent hair follicles. Experiments have confirmed that DP cells have multi-directional differentiation ability, which can not only spontaneously differentiate into myotubes, adipocytes, cardiomyocytes and neuron-like cells, but also differentiate into osteoblasts and adipocytes under induced conditions. Single-cell clones of DP also have the ability to differentiate between osteogenic and adipogenic fat.
Not only do multipotential cells exist in the dermis cells of rodents, but also a variety of cells with different differentiation potentials are found in human dermal tissues. A non-adherent growth cell, skin derived precursors (SKP), can be obtained from human dermis by trypsin digestion. SKP can be expanded and long-term subcultured in neural stem cell-related culture medium (can be cultured in vitro for more than 1 year); when SKP grows in vitro, it is expressed as suspended cell microspheres, and the marker intermediate filament protein expressing neural crest cells , but less expressed vimentin. SKP is able to differentiate into a variety of nerve cells such as neurons and glial cells. Not only that, but SKP can also differentiate into some mesoderm cells, such as adipocytes and smooth muscle cells. Although the specific distribution and fundamental role of SKP in the dermis has not been fully understood, its multiple germ layer (neuroectoderm and mesoderm) differentiation and self-renewal ability indicate that it is a dermis-derived adult stem cell. Bartsch et al. digested dermal tissue with collagenase to obtain adherent growth cells distinct from SKP, which can be cultured in vitro for a long time, and have three-way differentiation ability of osteogenesis, fat formation and muscle formation, showing mesenchymal stem cells. Characteristics.
Recent studies have shown that intermediate filament protein-negative cells derived from human dermis can also adhere to growth and long-term subculture. The dermal layer cells also express markers widely present in mesenchymal and mesoderm-derived cells, such as vimentin, CD10, CD49d, CD29, STRO-1, etc., and do not express markers of hematopoietic stem cells such as CD34 and CDl33. . When induced by traditional bone marrow stromal stem cell-inducing solution, fat cells, osteoblasts, and chondrocytes may be characterized: after 3 weeks of induction with the adipogenic induction solution, a large number of lipid droplets begin to appear in the cells; Appeared in uninduced cells, indicating that the formation of fat does not occur spontaneously. Molecular level detection also showed that the adipocyte-specific gene was activated 2 weeks after induction; the expression of osteogenic related genes ALP and OPN was detected 1 week after induction of osteogenic induction, and alkaline was detected. Phosphorase synthesis; expression of osteogenic specific markers (OCN, OPN, ON) was detected after 2 weeks, and obvious calcified nodules appeared after 4 weeks. The expression of cartilage-specific genes Agrrecan and type II collagen was detected 2 weeks after induction of chondrogenic induction, and histochemical and immunohistochemical staining confirmed the presence of these chondrocyte markers.
Moreover, the cloning of dermal layer cells revealed that most of the clonal cells were subcultured in vitro for a long time, and the chromosomes were not abnormal. After multi-directional induction of single cell clones (47 in total), it was found that 6.4% of the clones had osteogenic-to-cartilage-to-fat three-way differentiation ability, and 19.2% of the clones had bidirectional differentiation ability. These results indicate the presence of mesenchymal stem cells in the human dermis.
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