Swathi Balaji and Swathi Balaji
Research Associate, Center for Molecular Fetal Therapy, Cincinnati Children's Hospital Medical Center, USA
INTRODUCTION
More than 100 million patients acquire scars annually in the developed world, for which there is no
effective therapy. The fetal response to cutaneous injury is regenerative and can be recapitulated in
postnatal wounds by viral mediated over-expression of IL-10. We hypothesized that sustained
delivery of biologically active recombinant IL-10 could be facilitated through a more clinically translatable hydrogel
delivery system and used to promote regenerative healing in postnatal wounds.
METHODS
Optimal hydrogel composition for sustained IL-10 release was determined by evaluating in vitro multiple hydrogel
formulations containing hyaluronan/heparin sulphate and collagen loaded with recombinant IL-10. IL-10 release was
quantified (ELISA) and conditioned media from the gels were collected daily and used to treat adult dermal fibroblasts
to quantify pericellular matrix (PCM) formation and migration. In vivo, an excisional wound model in C57BL/6J mice
was used to evaluate the effects of hydrogel mediated IL-10 release on scar attenuation. 4mm wounds were evaluated at
28 days. Additional controls included, gel control, lentiviral IL-10 (LV-IL-10) and PBS (n=4/group). Histological
evaluation (H&E) and capillary density (CD 31+ caps/HPF) of uninjured skin and scars were performed (n=20) and
observed differences were used to establish a quantifiable parameters-based novel histologic scar scale, which was used
to compare treatments. Data presented as mean+/-SD, p-values by ANOVA.
RESULTS
HH10, a gel made of 2:1:1 (hyaluronan conjugated with heparan sulphate, type-I collagen and polyethylene glycol
diacrylate) and IL-10 (800ng/25ul) resulted in optimal sustained release of IL-10 in vitro, which is biologically active
and increased PCM formation and migration by fibroblasts. In vivo, histologic analysis demonstrated significant
differences between uninjured skin and scar in epidermal height and topography, nuclear orientation of the basal
keratinocytes, scar area, dermal appendages and vascular density (column A vs.B; p<.01). HH10 treatment resulted in
wound healing indistinguishable from surrounding skin, with significantly improved scar parameters compared to
characteristic scar in PBS wounds (column D vs. B; p<.01). HH10 restores epidermal and dermal scar parameters to the
levels observed in uninjured skin (column D vs. A; p=ns). Scar assessment reveals HH10 and viral over-expression of
IL-10 are equally potent in achieving attenuation of scar (column D vs. C; p=ns). Gel treatment without IL-10 improves
wound healing compared to PBS (column E vs. B; p<.05), but not to levels seen with HH10 or LV-IL-10 (column E vs.
D or C; p<.05).
CONCLUSIONS
Our novel quantifiable method to assess scars histologically demonstrated that sustained release of biologically active
recombinant IL-10 using a hyaluronan-based hydrogel (HH10) is capable of restoring epidermal and dermal parameters in postnatal wounds to the levels observed in unwounded skin, the benchmark of regenerative healing. HH10 obviates
some of the translatable concerns with IL-10 gene therapy, and has broad potential applications beyond the cosmetic
benefit, to any disease characterized by excessive fibroplasia.