A randomized clinical trial assessing the efficacy of single and multiple intralesional collagenase injections for treating contracted scars

Background:Scar contractions caused by trauma or burns can cause secondary physical dysfunction and disfigurement.Many minimally invasive methods for scar contraction have shown limited applicability and efficacy.This study investigated the feasibility and efficacy of intralesional collagenase injections for scar contraction treatment.Methods:Patients with contracted scars who had limited joint movement and physical disfiguration for>1 year were enrolled in this single-blind,randomized clinical trial from July 2017 to February 2018 at Shanghai Ninth People’s Hospital.Collagenase was injected into the firm-contracted scar(15 U/cm^(2))three times at 4-week intervals in the multiple treatment group and once in the single treatment group,and a placebo injection was performed in the control group.Scar length and skin texture were documented at the 4-and 12-week follow-ups.The safety of the collagenase treatment was also evaluated.Results:The contracted scar was significantly elongated after both single and multiple collagenase treatments.The results showed that,compared to a one-time treatment,repeated injections were more effective at 12 weeks,with an average improvement of 26.83(15.79%).At 12 weeks,78.9% of the patients in the multiple group and 52.9%in the single group achieved significant improvement at 12 weeks.No severe adverse events were observed.Conclusion:Intralesional collagenase injection showed promising results in improving scar contraction and provides an alternative treatment for patients.

3D-printed dermis-specific extracellular matrix mitigates scar contraction via inducing early angiogenesis and macrophage M2 polarization

Scar contraction frequently happens in patients with deep burn injuries.Hitherto,porcine dermal extracellular matrix(dECM)has supplied microenvironments that assist in wound healing but fail to inhibit scar contraction.To overcome this drawback,we integrate dECM into three-dimensional(3D)-printed dermal analogues(PDA)to prevent scar contraction.We have developed thermally gelled,non-rheologically modified dECM powder(dECMp)inks and successfully transformed them into PDA that was endowed with a micron-scale spatial structure.The optimal crosslinked PDA exhibited desired structure,good mechanical properties as well as excellent biocompatibility.Moreover,in vivo experiments demonstrated that PDA could significantly reduced scar contraction and improved cosmetic upshots of split thickness skin grafts(STSG)than the commercially available dermal templates and STSG along.The PDA has also induced an early,intense neovascularization,and evoked a type-2-like immune response.PDA’s superior beneficial effects may attribute to their desired porous structure,the well-balanced physicochemical properties,and the preserved dermis-specific ECM cues,which collectively modulated the expression of genes such as Wnt11,ATF3,and IL1β,and influenced the crucial endogenous signalling pathways.The findings of this study suggest that PDA is a clinical translatable material that possess high potential in reducing scar contraction.