An in vitro feasibility investigation considering primary human melanocytes for spray- grafting of freshly isolated autologous skin cells for burn treatment and a clinical case report

Abstract

A skin cell-spray grafting technique that enables the on-site application of freshly isolated autologous single cell suspensions was already applied in many cases on caucasian patients with low skin coloration. Our project hypothesis is that these suspensions contain keratinocytes and vital melanocytes, that are of particular interest for the treatment of patients of darker skin color. To test this, we applied an in vitro model, wherein the feasibility of i) isolating and ii) spraying of freshly isolated autologous melanocyte-keratinocyte cell suspensions was investigated. Primary human epidermal keratinocytes (HEKs) and melanocytes (MCs) were isolated from skin biopsies (n=8). Biochemical parameter, cell counts, cell morphology, growth behavior and immunofluorescence results were compared in two groups using MC cultures and co-cultures of MCs with HEKs. Case information on using the method clinically with one patient is included. The sprayed mixed cell suspensions proliferated in all groups without measurable loss of viability, and MCs exhibited a regular cell morphology in monoculture up to passage 4°. The sprayed MCs and HEKs demonstrated in vitro glucose and lactate metabolism that was comparable to the pipetted controls. In co-culture, well distributed CK14+ HEKs and NKI/beteb+ MCs could be demonstrated, which interacted in the in vitro model. The ratio of HEKs : MCs in our primary cultures were microscopically counted (n=8 each) as mean +/- SD 1,211,000 (+/- 574,343) HEK : 99,625 (+/- 59,025) MC; i.e., a ratio of approx. 12 : 1. Using the isolation method clinically for a patient with dark skin coloration after suffering severe second-degree burns shows a satisfying re-pigmentation of the resulting wound post healing. Freshly isolated spray-on melanocyte/keratinocyte suspensions provide for a considerable amount of viable HEKs and MCs. Using MCs in spray-grafting suspensions could represent a promising approach for treating severe partial-thickness burns and innovative therapy developments that also aim to address cosmetic aspects.