Cutaneous Radiation Injuries (CRIs) and wounds within an area of radiation exposure (combined injury, CI) are a significant concern for nuclear accidents and radiation combat/terrorist events. CRIs and CI present unique clinical challenges, and effective countermeasures are urgently needed. Here we describe a murine model of CRI and CI in C57BL/6 mice using 16.9 Gy thoracic X-ray irradiation (5.3 Gy/min, 160 kV) ± experimental wound administered immediately. Wound repair and radiation-induced dermatitis were assessed after irradiation. Our previous studies showed that genistein (200 mg/kg, s.c.), administered 24 h prior to irradiation prevented radiation injuries in two murine models. We investigated the effects of genistein in the CI model. Macroscopic and histological analyses showed that radiation significantly delayed wound closure, although wounds did not significantly alter the progression of radiation dermatitis. Genistein improved the early rate of wound closure and significantly reduced dermatitis in mice. Histological analysis showed that genistein improved skin structure and reduced inflammation and fibrosis. Immunohistochemistry showed that genistein attenuated radiation-induced cyclin-dependent kinase inhibitor 1 (p21/waf1) and α-smooth muscle actin and preserved K15 positive skin adult stem cells. These findings suggest that genistein may be an effective prophylactic against CRIs and CI.

Bioengineered dermal–epidermal composites (DECs) have demonstrated promise initiating skin regeneration and hair follicle neogenesis after injury. DECs in our work comprise a collagen matrix embedded with human dermal papilla cells (HDPCs) overlaid with human keratinocytes. HDPCs, as three-dimensional spheroids, enhance hair follicle formation, working in tandem with keratinocytes. Herein, 3D printed stamped PDMS microwell arrays were used as a strategy for spatially patterning dermal papilla spheroids in the dermal components of the DEC. DECs were transferred to cell culture media for 5 days followed by air–liquid interface culture for 2 days. Spheroid diameter, cell viability, and qPCR gene expression analyses were conducted. DECs were surgically grafted on immunocompromised mice, and healing was followed for 10 weeks. HDPCs cultured in the microwell arrays formed patterned viable spheroids and successfully transferred to the collagen dermal matrix. RNA analysis using qPCR showed upregulation of key HDPC markers (VCAN and BMP6) in DC microwell patterned HDPC spheroids compared to monolayers. This work represents a novel 3D printing strategy optimizing designing patterned HDPC spheroids in the extracellular matrix to regenerate functional human skin instead of scar tissue after injury.