دانلود رایگان مقاله انگلیسی سلول های بنیادی در پوست و مراقبت از پوست پیر و جوان - الزویر 2018

INTRODUCTION

Since the discovery of multipotent stem cells by Till and McCulloch in 1961,1 further elucidation of stem cells’ functions have been identified as both facilitating development of new cells and maintaining homeostasis of current normal cells. The activity of stem cells is stimulated by the start of tissue dysfunction. Several applications using these functions have been implemented in medicine already: reestablishing the hematopoietic lineage via bone marrow transplantation,2 development of stem-cell based therapy for type 1 diabetes3,4 and retinitis pigmentosa,5 and using stem cells to advance the cure for spinal cord injury.6 One important application of stem cell biology is how these cells can be used in the context of aging and age-related dysfunctions. During aging, DNA accumulates damage, impairing protein homeostasis, cell function and communication, as well as normal organ physiology.7 Another key hallmark to aging is the exhaustion or dysregulation of the endogenous stem cell population, which aids in maintaining tissue homeostasis and repair of injured tissues. Because aging is so intimately tied to stem cell integrity, one of the major goals of stem cell biology and regenerative medicine is how one can use these cells to reverse aging and the associated dysfunctions that come with it. Stem cells are undifferentiated or partially differentiated cells that are capable of dividing and generating differentiated and proliferative cells (Fig. 1). Stem cells range from pluripotent cells that are found in the inner cell mass of preimplantation blastocysts or isolated from other sources to unipotent progenitors such as fetal tissues, birth-associated tissues, or adult tissues. Several advances have been made to apply the unique traits of this variety of stem cell types.

SUMMARY

Currently, different skin therapies are emerging to treat and reverse the signs of aging. One approach is the utilization of growth factors to activate cell populations in the skin.40 Initially starting with plant stem cells, to conditioned medium growth factors, and finally to defined growth factors, there is increasing specificity in the growth factors being applied but there are several disadvantages to these 3 treatments. First is the lack of specificity to target cells such that these stem cells and growth factors can activate cells that are not normally involved in skin rejuvenation and be deleterious or tumorigenic. In addition, there are concerns with the efficacy and safety of these treatments as the composition of growth factors are not fully defined and there is a dearth of clinical research to affirm how effective these treatments are. Another aspect to their disadvantage is that all 3 activate aged basal stem cells that have accumulated photodamage, genetic mutations, and epigenetic alterations. By activating these cells, the differentiated keratinocytes will still possess these damages, thus not decelerating aging at an optimal rate.