Cutaneous gene therapy

Differential expression analysis of balding and nonbalding dermal papilla microRNAs in male pattern baldness with a microRNA amplification profiling method

BACKGROUND

  Male pattern baldness or androgenetic alopecia is a common disorder affecting almost 50% of men throughout their lifetime, with androgens and genetics having significant contributing aetiologies. In contrast to the positive regulatory effect of androgens on body hair growth, they are thought to alter scalp hair follicle behaviour pathophysiologically, leading to male pattern baldness. However, the exact mechanisms of this paradoxical action have not yet been elucidated. The role of microRNAs, a novel group of noncoding RNAs impacting almost every aspect of biology, health and human diseases, has been documented in hair follicle formation. In addition, their deregulation in cancer of the prostate, a target organ of androgens, has also been well established.

OBJECTIVES

To investigate the possible contribution of microRNAs in the pathophysiology of male pattern baldness.

METHODS

We initially screened microRNA expression profiles of balding and nonbalding hair follicle papillae with a sensitive microRNA cloning method, microRNA amplification profiling, and statistically analysed significant differentially expressed microRNAs in balding relative to nonbalding dermal papillae, with real-time polymerase chain reaction as a confirmatory method to quantify expression in eight individuals affected with the disorder.

RESULTS

  We detected the significant upregulation of miR-221, miR-125b, miR-106a and miR-410 in balding papilla cells.

CONCLUSIONS

  We found four microRNAs that could participate in the pathogenesis of male pattern baldness. Regarding the strong therapeutic potential of microRNAs and the easy accessibility of hair follicles for gene therapy, microRNAs are possible candidates for a new generation of revolutionary treatments.

A high-capacity, hybrid electro-microneedle for in-situ cutaneous gene transfer

Cutaneous gene transfer is limited by biological barriers such as skin and cellular membranes; complex approaches are required to overcome these biological barriers, simultaneously. Non-integrated systems that separate cutaneous permeation from intracellular transfection have been used to overcome skin and cellular barriers, respectively, however, do not provide sufficient doses of the gene to local tissue, resulting in inefficient gene transfer in-situ. Although integrated systems for cutaneous gene transfer are available, their safety has been questioned and it is difficult to transfer sufficient amounts of genes due to cumbersome sterilization procedures and the small size of the reservoir. Here, we demonstrate stepwise-aligned cutaneous permeation, cutaneous release, and intracellular transfection using a hybrid electro-microneedle (HEM), which designed as a monolithic hybrid assembly of a dissolving microneedle and an electrode, anomalously. Furthermore, as proof-of-principle, we use the HEM for in-situ cutaneous transfer of p2CMVmIL-12 to successfully treat B16F10 subcutaneous tumors in a mouse model. The HEM described herein holds great promise for cutaneous gene therapy of cancers and for vaccines.

Combined gene and stem cell therapy for cutaneous wound healing

In current medical practice, wound therapy remains a clinical challenge and much effort has been focused on the development of novel therapeutic approaches for wound treatment. Gene therapy, initially developed for treatment of congenital defects, represents a promising option for enhancing wound repair. In order to accelerate wound closure, genes encoding for growth factors or cytokines have shown the most potential. The majority of gene delivery systems are based on viral transfection, naked DNA application, high pressure injection, and liposomal vectors. Besides advances stemming from breakthroughs in recombinant growth factors and bioengineered skin, there has been a significant increase in the understanding of stem cell biology in the field of cutaneous wound healing. A variety of sources, such as bone marrow, umbilical cord blood, adipose tissue and skin/hair follicles, have been utilized to isolate stem cells and to modulate the healing response of acute and chronic wounds. Recent data have demonstrated the feasibility of autologous adult stem cell therapy in cutaneous repair and regeneration. Very recently, stem cell based skin engineering in conjunction with gene recombination, in which the stem cells act as both the seed cells and the vehicle for gene delivery to the wound site, represents the most attractive field for generating a regenerative strategy for wound therapy. The aim of this article is to discuss the use and the potential of these novel technologies in order to improve wound healing capacities.

Stem cells and tissue-engineered skin

Advances in tissue engineering of skin are needed for clinical applications (as in wound healing and gene therapy) for cutaneous and systemic diseases. In this paper we review the use of epidermal stem cells as a source of cells to improve tissue-engineered skin. We discuss the importance and limitations of epidermal stem cell isolation using biomarkers, in quest of a pure stem cell preparation, as well as the culture conditions necessary to maintain this purity as required for a qualitatively superior and long-lasting engineered skin. Finally, we review the advantages of using additional multipotent stem cell sources to functionally and cosmetically optimize the engineered tissue.

(Neuro-)endocrinology of epithelial hair follicle stem cells

The hair follicle is a repository of different types of somatic stem cells. However, even though the hair follicle is both a prominent target organ and a potent, non-classical site of production and/or metabolism of numerous polypetide- and steroid hormones, neuropeptides, neurotransmitters and neurotrophins, the (neuro-)endocrine controls of hair follicle epithelial stem cell (HFeSC) biology remain to be systematically explored. Focussing on HFeSCs, we attempt here to offer a "roadmap through terra incognita" by listing key open questions, by exploring endocrinologically relevant HFeSC gene profiling and mouse genomics data, and by sketching several clinically relevant pathways via which systemic and/or locally generated (neuro-)endocrine signals might impact on HFeSC. Exemplarily, we discuss, e.g. the potential roles of glucocorticoid and vitamin D receptors, the hairless gene product, thymic hormones, bone morphogenic proteins (BMPs) and their antagonists, and Skg-3 in HFeSC biology. Furthermore, we elaborate on the potential role of nerve growth factor (NGF) and substance P-dependent neurogenic inflammation in HFeSC damage, and explore how neuroendocrine signals may influence the balance between maintenance and destruction of hair follicle immune privilege, which protects these stem cells and their progeny. These considerations call for a concerted research effort to dissect the (neuro-)endocrinology of HFeSCs much more systematically than before.