Depilatory double-disc mouse model for evaluation of vesicant dermal injury pharmacotherapy countermeasures

Background:Sulfur mustard(SM)is a chemical warfare vesicant that severely injures exposed eyes,lungs,and skin.Mechlorethamine hydrochloride(NM)is widely used as an SM surrogate.This study aimed to develop a depilatory double-disc(DDD)NM skin burn model for investigating vesicant pharmacotherapy countermeasures.Methods:Hair removal method(clipping only versus clipping followed by a depilatory),the effect of acetone in the vesicant administration vehicle,NM dose(0.5-20μmol),vehicle volume(5-20μl),and time course(0.5-21 days)were investigated using male and female CD-1 mice.Edema,an indicator of burn response,was assessed by biopsy skin weight.The ideal NM dose to induce partial-thickness burns was assessed by edema and histopathologic evaluation.The optimized DDD model was validated using an established reagent,NDH-4338,a cyclooxygenase,inducible nitric oxide synthase,and acetylcholinesterase inhibitor prodrug.Results:Clipping/depilatory resulted in a 5-fold higher skin edematous response and was highly reproducible(18-fold lower%CV)compared to clipping alone.Acetone did not affect edema formation.Peak edema occurred 24-48 h after NM administra-tion using optimized dosing methods and volume.Ideal partial-thickness burns were achieved with 5μmol of NM and responded to treatment with NDH-4338.No dif-ferences in burn edematous responses were observed between males and females.Conclusion:A highly reproducible and sensitive partial-thickness skin burn model was developed for assessing vesicant pharmacotherapy countermeasures.This model pro-vides clinically relevant wound severity and eliminates the need for organic solvents that induce changes to the skin barrier function.

The role of crystallinity on differential attachment/ proliferation of osteoblasts and fibroblasts on poly （caprolactone-co-glycolide） polymeric surfaces

The objective of the present study is to systematically evaluate the role of polymer crystallinity on fibroblast and osteoblast adhesion and proliferation using a series of poly（caprolactone-co-glycolide） （PCL/PGA） polymers. PCL/PGA polymers were selected since they reflect both highly crystalline and amorphous materials. PCL/PGA polymeric materials were fabricated by compression molding into thin films. Five compositions, from PCL or PGA to intermediate copolymeric compositions of PCL/PGA in ratios of 25：75, 35：65 and 45：55, were studied. Pure PCL and PGA represented the crystalline materials while the copolymers were amorphous. The polymers/copolymers were characterized using DSC to assess crystallinity, contact angle measurement for hydrophobicity, and AFM for nanotopography. The PCL/PGA films demonstrated similar hydrophobicity and nanotopography whereas they differed significantly in crystallinity. Cell adhesion to and proliferation on PCL/PGA films and proliferation studies were performed using osteoblasts and NIH-3T3 fibroblasts. It was observed that highly crystalline and rigid PCL and PGA surfaces were significantly more efficient in supporting fibroblast growth, whereas amorphous/flexible PCL/PGA 35：65 was significantly more efficient in supporting growth of osteoblasts. This study demonstrated that while chemical composition, hydrophobicity and surface roughness of PCL/PGA polymers were held constant, crystallinity and rigidity of PCL/PGA played major roles in determining cell responses.