Hair regeneration from transected follicles in duplicative surgery: rate of success and cell populations involved

Follicular Unit Extraction (FUE) Hair Transplant: Curves Ahead

The hair transplant has become widely popular aesthetic procedure. Follicular unit transplantation (FUT) and follicular unit extraction (FUE) are two commonly used and accepted techniques. FUT requires excision of strip of tissue from occipital donor area leading to linear scar. To overcome scarring and other complications of FUT, FUE technique has been attempted which involves harvesting of small individual follicular units. Hair transplantation has been successfully used in correction of alopecia, cleft lip scars, post-burn or surgical scars, vitiligo and as an adjuvant to other maxillofacial procedures. FUE demands greater skills and orientation but can yield excellent results in experienced hands. Several maxillofacial surgeons have incorporated hair transplantation procedure in their aesthetic practice successfully. Sound knowledge of surgical technique, armamentarium and proper surgical planning are essential for desired results. The aim of this article is to explain FUE technique, risk and complications, holding solutions and other associated factors in detail. A simple protocol has been put forth for reference and for better understanding of the technique.

Towards expansion of human hair follicle stem cells in vitro

OBJECTIVES

Multipotential human hair follicle stem cells can differentiate into various cell lineages and thus are investigated here as potential autologous sources for regenerative medicine. Towards this end, we have attempted to expand these cells, directly isolated from minimal amounts of hair follicle explants, to numbers more suitable for stem-cell therapy.

MATERIALS AND METHODS

Two types of human follicle stem cells, commercially available and directly isolated, were cultured using an in-house developed medium. The latter was obtained from bulge areas of hair follicles by mechanical and enzymatic dissociation, and was magnetically enriched for its CD200(+) fraction. Isolated cells were cultured for up to 4 weeks, on different supports: blank polystyrene, laminin- and Matrigel(TM) -coated surfaces.

RESULTS

Two-fold expansion was found, highlighting the slow-cycling nature of these cells. Flow cytometry characterization revealed: magnetic enrichment increased the proportion of CD200(+) cells from initially 43.3% (CD200+, CD34: 25.8%; CD200+, CD34+: 17.5%) to 78.2% (CD200+, CD34: 41.5%; CD200+, CD34+: 36.7%). Enriched cells seemed to have retained and passed on their morphological and molecular phenotypes to their progeny, as isolated CD200(+) presenting cells expanded in our medium to a population with 80% of cells being CD200(+): 51.5% (CD200(+), CD34(-)) and 29.6% (CD200(+), CD34(+)).

CONCLUSIONS

This study demonstrates the possibility of culturing human hair follicle stem cells without causing any significant changes to phenotypes of the cells.

Functional characterization of highly adherent CD34+ keratinocytes isolated from human skin

Compared to murine models, data on cells responsible for the homeostasis of human epidermis are scarce and often contradictory. Given the conflicting results and the availability of clinical grade protocols to purify CD34 cells from a given tissue, we pursued to phenotypically characterize human epidermal CD34+ population. After magnetic separation of whole skin CD34+ and CD34- cell fractions and selection for cells highly adherent to extracellular matrix, both CD34+/- fractions retained the ability to form a stratified epidermis in organotypic cultures and presented similar in vitro migratory phenotypes. However CD34- cells showed higher clonogenic potential and in vitro proliferative capacity. These results indicated that CD34- cell fraction contains stem/early progenitor cells, while CD34+ cells might be a transit-amplifying precursor for hair follicle (HF) sheath cells. The ability to isolate living cells using differential cell adhesion and surface markers provides an opportunity to study cells from different morphological regions of the HF.