Adult stem cells also known as somatic stem cells, are the undifferentiated cells that reside in specialized tissue and contain the major properties of stem cells. Their ability to regenerate, is however, limited in magnitude and multipotency. Cells remain in specialized environment called niche, where they exist connected to supporting cells. It is important to protect them from harmful external stimuli. While waiting for an activation signal, adult stem cells should be inactive. Therefore, research shows that the adult stem cells helps in tissue regeneration and repair.
Mechanism of Adult Stem Cells
Tissue-specific adult stem cells reproduce, migrate from the niche and differentiate to replace old cells according to organ demand. Hence, maintaining the function and structure of the organ. Further these cells repair damage in many organs such as liver, skin, kidney and bone marrow . However, such regenerative process cannot repair severe damage like cerebral ischemia or myocardial infarction. As these type of damage is usually permanent and non-repairable in spite of the presence of stem cells. Possibly, tissue-specificity affects the fate of adult stem cells and their parent cells in normal and pathological state to give rise to limit cell differentiation and in vivo survival.
A review by A. Klimczak and U. Kozlowska, which gives an overview of the present knowledge of biology of adult mesenchymal stem and parent cells in organs such as bone marrow, liver, skeletal muscle, skin, heart, and lung. Both, ability of stem cell to differentiate and paracrine influence on other tissue-resident cells can be reviewed as trigger for organ regeneration and repair. D. Chen et al. analyze the role of adult mesenchymal stem cells in healing wounds and specifically on their contribution to re-epithelialization. The anti-inflammatory action of stem cell can be a determinant of proper healing of wounds. Tissue engineering with use of skin-compatible biomaterial implanted with stem cells in skin, is another way of organ regeneration.
The present understanding of adult tissue-specific stem cell biology can provide the basis for experimental and therapeutic tissue regeneration and repair. The availability and ease of cell isolation is determine by their source. Therefore, origin of mesenchymal stem cells of blood, bone marrow and adipose tissue are most studied population of adult stem cells. Use of tissue-specific adult stem cells is way more acceptable and safe than embryonic or induced pluripotent stem cells. Hence, they are closer to use for medical application. For cell isolation, growth, modification and transplantation, only approved and verified procedures should be introduced in clinic. Also, ethical and legal value should be consider while using human tissue.