Reformation of organized epidermal structure by transplantation of suspensions and cultures of epidermal and dermal cells.

The development of epidermis and epidermal appendages from dissociated cells of neonate mouse skin was examined by transplantation of cell suspensions to subdermally prepared, protected graft beds. Using Ficol gradients and culture procedures, we prepared subfractions of primary cell suspensions consisting of essentially pure epidermal cells or fibroblasts. Reformation of an epithelium structurally similar to the epidermis was observed from transplanted epidermal-cell suspensions, but formation of hair follicles and development of normal epidermal microarchitecture was observed only when epidermal cells were transplanted together with cells of dermal origin. This pattern was observed following transplantation of either fresh-cell isolates or cells cultured up to 7 days prior to transplantation.

Characteristics of chemically transformed mouse epidermal cells in vitro and in vivo.

Primary cultures of epidermal cells from newborn mouse skin have been established. These cultures proliferate and express typical epidermal functions for limited time in vitro. The cultured cells keratinize and exhibit strong reactivity with an epidermis specific membrane antiserum. These cells can be transformed with DMBA either in standard cultures or more easily in cultures using 3T3 feeder cells. Transformed cells have increased proliferation rate. They do not pile up or form multilayered cultures like normal counterparts. They also keratinize less. When transformed cells were grown in the air on collagen gels they formed irregular clumps with central (horn-pearl) keratinization whereas normal controls formed stratified structures. Transofmred cells exhibited reduced reactivity with tissue specific membrane antiserum. There was masking or rearrangement of tissue specific membrane antigens with simultaneous exposition of new fetal-like antigens. Their reactivity with histocompatibility antisera was only slightly reduced. Transformed cells had both numerical and structural chromosome aberrations. They grew in soft agar and they induced tumors upon transplantation in the convenient host. When transplanted as cultures (on collagen) or as suspensions into the host, transformed cells were able to form epithelial cell cords invading the underlying mesenchyme with histological aspect typical of carcinoma. Cell cultures derived from in vivo DMBA induced tumors behaved like in vitro transformed cells.

[Skin transplantation in the study of chemical carcinogenesis. III. Reduced papilloma-formation after initiation during epidermal hyperplasia induced by skin grafting or by a single application of the cocarcinogen TPA].

Skin autografting or a single painting with the cocarcinogen TPA was used to induce epidermal hyperplasia in the back skin of C3H mice. Initiation by intragastric application of the carcinogen DMBA during this state of hyperplasia and subsequent promotion by repeated application of the cocarcinogen TPA led to decreased papilloma-formation, as compared to mice of a control group which had not been pretreated before initiation. Reports by others referring to increased susceptibility of replicating epidermal cells to the effect of initiation thus cannot be confirmed. The reduction of papilloma-formation can most probably be ascribed to effects of local inflammation, either preferentially but unspecifically damaging initiated cells, or facilitating a specific immune response against tumor-associated transplantation antigens of prospective tumor cells.