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Dermal Cells Promote Hair Follicle Stem Cell Containing Skin Grafts

A new study finds that dermal cells promote proper skin formation and better wound healing in hair follicle stem cell-containing skin grafts

The Role of Wnt7b in Hair Follicle Regulation Delineated

Study suggests that Wntb7 has an intrinsic non-redundant function in hair follicle cycle length and HFSC activation, having potential implications in HF-related diseases and therapeutics.

“Hair, Hair” to Tbx1 – An RNA interference screen uncovers a new molecule in stem cell self-renewal and long-term regeneration

 

Adult or tissue-specific stem cells play major roles in tissue regeneration during normal aging and also during disease. However, the complex multi-factor mechanisms which regulate stem cell self-renewal in adult tissues are relatively unknown. To resolve this, researchers from the laboratory of Elaine Fuchs at the Howard Hughes Medical Institute, The Rockefeller University, New York utilised an RNA-interference-based loss-of function screen in hair follicle stem cells (HF-SCs) to better understand the factors which may govern self-renewal and regenerative potential in stem cells (Chen et al).

Stem Cell Cause of Baldness??

While not being a life threatening condition, male pattern baldness affects (or will affect!) a great number of males and can also affect females too. A recent study in the Journal of Clinical Investigation by Garza et al., from the lab of George Cotsarelis at the University Of Pennsylvania School Of Medicine places the blame for this condition squarely at the feet of our stem cells. Common baldness (or Androgenetic alopecia (AGA)), is characterized by a marked decrease in hair follicle size but this had not previously been linked to the stem cells which reside within the hair follicle. The study found that the resident hair follicle stem cells remain at the same number in bald and control patients but the conversion of stem cells to the progenitor cells required for cell and hair growth was diminished in bald patients, leading to the miniaturisation of the hair follicle stem cell compartment. Therefore strategies to coax the stem cells into producing more hair follicle progenitor cells may generate bigger hair follicles capable of restoring hair growth.

Forthcoming article in Stem Cells - From Hair to Cornea: Towards the Therapeutic Use of Hair Follicle-Derived Stem Cells in the Treatment of Limbal Stem Cell Deficiency

By Stuart P. Atkinson

Many laboratories throughout the world are working with embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) as sources of cells for replacement therapy in human disease. The necessity for patient specificity of these cells is generally a significant problem, which may be overcome in the case of iPSCs if they ultimately prove to be a suitable replacement for ESCs. However, even if they do prove to be similar, differentiation protocols are highly inefficient and require long culture periods in vitro and expensive culture conditions. Orthologous adult stem cell therapy, that is treatment of the patient with his own stem cells, is a strategy that has interested many groups and their potential for transdifferentiation and use in therapy is tantalizing.

‘Mir’ roles for miR-302 in cell cycle and tumorigenesis suppression

From Cancer Research

The microRNA miR-302 is implicated in the regulation of stemness and pluripotency, somatic cell reprogramming and more recently the global DNA demethylation and histone methylation which occurs during somatic cell reprogramming (see Splitting hairs: Follicking about with mir-302). Results from the same group in California now published in Cancer Research go on to reveal more about the action of this small, non-coding RNA – this time, its role in suppressing the human stem cell cycle and tumorigenicity.

Splitting hairs: Follicking about with mir-302

By Carla Mellough

Continuing on with our recent focus on microRNA (miRNA) and induced pluripotency (see ‘Reprogramming the methods that induce pluripotency’), a recent article published in the September advance issue of Nucleic Acids Research from David Wu’s group (WJWU and LYNN Institute for Stem Cell Research) in California may shed light on the mechanisms that govern somatic cell reprogramming. In this article Lin et al. uncover a regulatory mechanism that controls global DNA demethylation and histone methylation, a requirement for the reprogramming of somatic cells. Global demethylation is an event largely associated with early zygote development and is key for the establishment of stem cell pluripotency, but how cell stemness is reset in somatic cells during reprogramming is not yet clearly understood. Of the four Yamanaka factors, two (Oct3/4 and Sox2) are essential for reprogramming to occur and both of these were recently shown to be crucial for expression of the miRNA Mir-302. MiRNAs are a class of non-coding RNAs that suppress the translation of target messenger RNAs. Mir-302 expression, encoded for within a region of chromosome 4 that is associated with longevity, is high in both human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC) with mir-302 downregulation accompanying cell differentiation>. This suggests a role for mir-302 in the regulation of stemness and pluripotency (alongside other stem cell-associated miRNAs) and therefore also the reversion of lineage restricted cells to a pluripotent state.

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