Proliferation of human embryonic and fetal epidermal cells in organ culture

Abstract

The morphology of human embryonic and fetal skin growth in organ culture at the air-medium interface was examined, and the labeling indices of the epidermal cells in such cultures were determined. The two-layered epidermis of embryonic specimens increased to five or six cell layers after 21 days in culture, and the periderm in such cultures changed from a flat cell type to one with many blebs. The organelles in the epidermal cells remained unchanged. Fetal epidermis, however, differentiated when grown in this organ culture system from three layers (basal, intermediate, and periderm) to an adult-type epidermis with basal, spinous, granular, and cornified cell layers. Keratohyalin granules, lamellar granules, and bundles of keratin filaments, organelles associated with epidermal cell differentiation, were observed in the suprabasal cells of such cultures. The periderm in these fetal cultures formed blebs early but was sloughed with the stratum corneum in older cultures. The rate of differentiation of the fetal epidermis in organ culture was related to the initial age of the specimen cultured, with the older specimens differentiating at a faster rate than the younger specimens. Labeling indices (LIs) of embryonic and fetal epidermis and periderm were determined. The LI for embryonic basal cells was 8.5% and for periderm was 8%. The fetal LIs were 7% for basal cells, 1% for intermediate cells, and 3% for periderm. The ability to maintain viable pieces of skin in organ culture affords a model for studying normal and abnormal human epidermal differentiation from fetal biopsies and for investigating proliferative diseases.

A model system for long-term serum-free suspension organ culture of human fetal tissues: experiments on digits and skin from multiple body regions

“…With the present modifications to the original SOC system, epidermal and dermal histogenesis of digits and skin grown in vitro mimic the in vivo process of differentiation more closely than that observed in previous studies (Bickenbach and Holbrook 1986;Fisher and Holbrook 1987;Holbrook and Minami 1991). The establishment of a serum-free SOC system is advantageous for in vitro tissue manipulation studies in investigations of the morphogenesis and differentiation of human fetal cutaneous tissues.…”

“…Our present results indicate that, for optimal viability, preservation of structural tissue integrity, and substantial histogenesis of human fetal digits and skin in SOC, the most reliable conditions are serum-free DMEM-F12 supplemented to a final concentration of 6 mg/ml BSA, 0.1 mM nonessential amino acids, 75 U/ml penicillin G, 75 mg/ml streptomycin sulfate, and 1.25 mg/ml fungizone, and an atmosphere of 5% O 2 , 45% O 2 , 50% N 2 . The nutrient-rich medium DMEM-F12 consistently out-performs its chemical relatives, viz., DMEM and MEM, which have been used in other human skin organ culture systems, and William's E medium, which has been used for culturing individual human adult hair follicles (Bickenbach and Holbrook 1986;Fisher and Holbrook 1987;Philpott et al 1990;Holbrook and Minami 1991;Kondo et al 1990;Martikainen et al 1992).…”

Apoptosis in human skin development: Morphogenesis, periderm, and stem cells

“…Differential proliferation of epidermal keratinocytes during these events is well established in human (Bickenbach and Holbrook, 1986)) mouse and chick skin (Wessells, 1965;Sawyer, 1972;Sengel, 1983). Another major developmental process that may function in the morphogenesis of the skin, but has not been emphasized, is apoptosis, often termed programmed cell death (PCD) in developing tissues.…”

Epidermal Lamellar Granules

“…Production of LGs, revealed by TEM, has been used as an indicator of differentiation in keratinocyte cultures [13][14][15][16][17][18][19][20][21]. Formation of normal LGs has been considered a hallmark of differentiation in organ culture [13], stratified keratinocyte cultures [16,17,[19][20][21], and organotypic skin cultures [14,15,18].…”

“…Formation of normal LGs has been considered a hallmark of differentiation in organ culture [13], stratified keratinocyte cultures [16,17,[19][20][21], and organotypic skin cultures [14,15,18].…”