Microfluidic Isolation of CD34-Positive Skin Cells Enables Regeneration of Hair and Sebaceous Glands In Vivo.

Skin stem cells resident in the bulge area of hair follicles and at the basal layer of the epidermis are multipotent and able to self-renew when transplanted into full-thickness defects in nude mice. Based on cell surface markers such as CD34 and the α6-integrin, skin stem cells can be extracted from tissue-derived cell suspensions for engraftment using the gold standard cell separation technique of fluorescence-activated cell sorting (FACS). This paper describes an alternative separation method using microfluidic devices coated with degradable antibody-functionalized hydrogels. The microfluidic method allows direct injection of tissue digestate (no preprocessing tagging of cells is needed), is fast (45 minutes from injected sample to purified cells), and scalable. This method is used in this study to isolate CD34-positive (CD34+) cells from murine skin tissue digestate, and the functional capability of these cells is demonstrated by transplantation into nude mice using protocols developed by other groups for FACS-sorted cells. Specifically, the transplantation of microfluidic isolated CD34+ cells along with dermal and epidermal cells was observed to generate significant levels of hair follicles and sebaceous glands consistent with those observed previously with FACS-sorted cells.

Variability of hair coat and skin traits as related to adaptation in Criollo Limonero cattle.

The variation in hair coat and skin histology traits of Criollo Limonero cattle was analyzed using 213 Criollo Limonero females. Skin biopsies were obtained from slick-haired (N=16) and normal-haired (N=14) animals. Measured traits included hair length (HL), color coat (CC), number of hair follicles per square centimeter (NHF), sweat glands per square centimeter (NSG), sweat glands size (SGS), sebaceous glands per square centimeter (NSBG), blood vessels per square centimeter (NBV), and thickness of epidermis (TE). Hair length differed (P<0.001) between slick- and normal-haired animals (4.9 ± 0.12 vs 10.9 ± 0.20, respectively). Differences (P<0.01) in CC (Bayo = 144/67.6% vs Red = 69/32.4%) and HL (slick-haired = 199/93.4% vs normal-haired = 14/6.5%) were found. Distribution of slick- and normal-haired animals differed (P<0.01) between bayo-coated and red-coated (139/62.2% vs 9/4.2%; respectively). Most (P<0.05) red-coated animals belonged to a single family. No differences (P>0.05) were found between slick-haired and normal-haired animals in NHF (637 ± 164 vs 587 ± 144, respectively), NSG (556 ± 134 vs 481 ± 118, respectively), NSBG (408 ± 87 vs 366 ± 77, respectively), NBV (1628 ± 393 vs 1541 ± 346, respectively), and TE (1.24 ± 0.14 vs 1.32 ± 0.12, respectively). However, SGS was greater (P<0.01) in slick-haired than normal-haired animals. In conclusion, Criollo Limonero cattle are predominantly bayo-coated, slick-haired, with a reduced number of hair follicles relative to Zebu cattle, sweat and sebaceous glands in proportion to hair follicle numbers, and with a high blood flow irrigating the skin. There is a sub-group of red-coated animals with yellow or cream skin, thicker epidermis, and with a higher frequency of normal-haired animals. It appears that the slick hair gene has been favored by natural selection in this breed.

Seasonal sebaceous patch in the nectar-feeding bats Leptonycteris curasoae and L. yerbabuenae (Phyllostomidae: Glossophaginae): phenological, histological, and preliminary chemical characterization.

Many species of bats secrete a wide variety of substances, frequently associated with olfactory communication. We characterized a seasonal phenomenon of dorsal sebaceous secretion in the Curaçaoan long-nosed bat, Leptonycteris curasoae, in Venezuela, and the lesser long-nosed bat, Leptonycteris yerbabuenae, in Mexico. The phenology of the sebaceous patch was determined, a histological analysis of the affected area was conducted using specimens of L. curasoae from Venezuela, and finally, a preliminary chemical characterization of the substance secreted was performed combining histochemical techniques with gas chromatography and mass spectrometry analyses. The sebaceous patch was detected exclusively in male adult specimens. Individuals presenting it had a variable area of fur covered with a fatty and odoriferous substance at the level of the interscapular zone. Occurrence of the sebaceous patch was cyclical and coincided with the mating season in Venezuela and Mexico. The following histological changes associated with occurrence of the patch were observed: increase of epidermis thickness and decrease of dermis and hypodermis thicknesses, increase in density of sebaceous glands, increase of percentage of skin covered by sebaceous glands, increase of size of sebaceous glands previous to secretion followed, and increase of the sebum volume within sebaceous glands previous to secretion. Several compounds tentatively identified as fatty acids, cholestanes and cholesterol were present in the sebaceous secretion. Based on the evidence obtained, we hypothesize that the sebaceous patch could be involved in olfactory communication, possibly related to mating behavior in these bats.

Histology of the sternal and suprapubic skin areas in lion tamarins (Leontopithecus sp. Callitrichidae-primates).

Though knowledge regarding the biology and morphology of lion tamarins is scarce in the literature, it is very important for their conservation. This paper focuses on the anatomical and histological aspects of the glands involved in the scent-marking behavior of lion tamarins. It examines the histological aspects of sternal and suprapubic skin sections of specimens that were preserved in formaldehyde and were the property of the Rio de Janeiro Primatology Center Museum. Eighteen specimens from three lion tamarin (Leontopithecus sp.) species (L. rosalia, L. chrysomelas, and L. chrysopygus) were analyzed. Both sexes were represented, and macroscopic hypertrophy was quantified by direct observation of the tegument on the sternal area and classified as discrete, moderate, or accentuated for each specimen. The skin of both sexes had a high degree of histological resemblance to that of other primates, including humans. The epidermis presented stratified squamous keratinous epithelia, with a few cellular layers and dermis with cutaneous appendages (i.e., hair follicles and both sebaceous and sweat glands). The dermal papillae were short, and the sebaceous and apocrine sweat glands resembled those of humans. These glands were present in the dermis of the analyzed skin fragments of both sternal and suprapubic regions in great numbers. Furthermore, we were able to establish a relationship between the macroscopic appearance of the sternal tegument and the degree of microscopic gland hyperplasia.

Mechanism of percutaneous absorption

The structure and diffusion parameters of epidermis have been measured and emplyed in a mathematical analysis of skin diffusion. The ratio of the total amount of material capable of diffusing through the follicles and sweat duets to the amount through the stratum corneum has been computed. Shunt diffusion (through duets and folicles) was found to be overwhelmingly dominant in the initial transient stage of diffusion. Bulk diffusion through the intact stratum corneum was found to be dominant in the steady state stage. Concentration levels in the stratum corneum and the viable epidermis have been computed for steady state and for the transient period. The effect of the composite nature of the skin diffusion barrier and of the partition coefficient are included. The recognition of transient diffusion occurring primarily via follicles and ducts and steady state diffusion primarily through the intact stratum crneum has been shown to result in a considerably more self-consistent and orderly treatment of the process of percutaneous absorption.