GHK tested for stopping stem cell differentiation

GHK-Cu tested for stimulating stem cell differentiation

GHK reduced the clonogenic potential of stem cells by 78%

GHK-Cu increased cell copper by 2162% above the control value and caused stem cell differentiation

Methods of controlling proliferation and differentiation of stem and progenitor cells, United States Patent:  6,962,698, Peled, Tony, Fibach, Eitan, Treves; Avi, Gamida Cell Ltd. (Jerusalem, IL) and Hadasit Medical Research Services and Development, Ltd. (Jerusalem, IL)

GHK-copper activated adult stem cells by increasing integrins, P63, and PCNA. This increased keratinocyte proliferation.

Arch Dermatol Res. 2009 Apr;301(4):301-6. Copper-GHK increases integrin expression and p63 positivity by keratinocytes. Kang YA, Choi HR, Na JI, Huh CH, Kim MJ, Youn SW, Kim KH, Park KC. Department of Dermatology, Seoul National University College of Medicine, Yeongeon-dong, Jongno-gu, Seoul, Republic of Korea.

Glycyl-L-histidyl-L-lysyl (GHK) possesses a high affinity for copper(II) ions, with which it spontaneously forms a complex (copper-GHK). It is well known that copper-GHK plays a physiological role in the process of wound healing and tissue repair by stimulating collagen synthesis in fibroblasts. This study was conducted to investigate the effects of copper-GHK on keratinocytes. Proliferative effects were analyzed and hematoxylin and eosin staining and immunohistochemistry were conducted to evaluate the effects of copper-GHK in skin equivalent (SE) models. In addition, western blotting was performed. In monolayer cultured keratinocytes, copper-GHK increased the proliferation of keratinocytes. When the SE models were evaluated, basal cells became cuboidal when copper-GHK was added. Immunohistochemical analysis revealed that copper-GHK increased proliferating cell nuclear antigen (PCNA) and p63 positivity. Furthermore, the expression of integrin alpha6 and beta1 increased in SE models, and these results were confirmed by Western blotting. The results of this study indicate that treatment with copper-GHK may increase the proliferative potential of basal keratinocytes by modulating the expression of integrins, p63 and PCNA. In addition, increased levels of p63, a putative stem cell marker of the skin, suggests that copper-GHK promotes the survival of basal stem cells in the skin.

Cell Stem Cell. 2009 Jul 2;5(1):64-75. TAp63 prevents premature aging by promoting adult stem cell maintenance. Su X, Paris M, Gi YJ, Tsai KY, Cho MS, Lin YL, Biernaskie JA, Sinha S, Prives C, Pevny LH, Miller FD, Flores ER. Department of Molecular and Cellular Oncology, Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

The cellular mechanisms that regulate the maintenance of adult tissue stem cells are still largely unknown. We show here that the p53 family member, TAp63, is essential for maintenance of epidermal and dermal precursors and that, in its absence, these precursors senesce and skin ages prematurely. Specifically, we have developed a TAp63 conditional knockout mouse and used it to ablate TAp63 in the germline (TAp63(-/-)) or in K14-expressing cells in the basal layer of the epidermis (TAp63(fl/fl);K14cre+). TAp63(-/-) mice age prematurely and develop blisters, skin ulcerations, senescence of hair follicle-associated dermal and epidermal cells, and decreased hair morphogenesis. These phenotypes are likely due to loss of TAp63 in dermal and epidermal precursors since both cell types show defective proliferation, early senescence, and genomic instability. These data indicate that TAp63 serves to maintain adult skin stem cells by regulating cellular senescence and genomic stability, thereby preventing premature tissue aging.

Cellular senescence is a distinctive form of cell cycle arrest that has been suggested to modulate the processes of tumor suppression and aging. Though a detailed understanding of the cellular machinery regulating this process is emerging, a more thorough understanding of the key players linking senescence to organismal aging is needed. The recent discovery that loss of the p53-related protein p63 induces cellular senescence and causes features of accelerated aging provides further evidence that cellular senescence is intimately linked with organismal aging, and identifies p63 as a key regulator of both of these processes.

The p53 family member p63 comprises multiple isoforms and is critical for stratified epithelial development. In this issue of Cell Stem Cell, by generating isoform-specific knockout mice, Su et al. (2009) reveal pivotal roles for TAp63 in the maintenance of dermal and epidermal precursors, genomic stability, and organismal longevity

The distinguishing feature of adult stem cells is their extraordinary capacity to divide prior to the onset of senescence. While stratified epithelia such as skin, prostate, and breast are highly regenerative and account disproportionately for human cancers, genes essential for the proliferative capacity of their stem cells remain unknown. Here we analyze p63, a gene whose deletion in mice results in the catastrophic loss of all stratified epithelia. We demonstrate that p63 is strongly expressed in epithelial cells with high clonogenic and proliferative capacity and that stem cells lacking p63 undergo a premature proliferative rundown. Additionally, we show that p63 is dispensable for both the commitment and differentiation of these stem cells during tissue morphogenesis. Together, these data identify p63 as a key, lineage-specific determinant of the proliferative capacity in stem cells of stratified epithelia.