Dynamic changes of autophagy during hypertrophic scar formation and the role of autophagy intervention

Background:The role of autophagy in the formation of hypertrophic scars(HS)remains unclear.This study aimed to explore the role and potential mechanism of autophagy during the development of HS.Methods:RNA and protein expression levels of Beclin-1,p62,and LC3II in normal skin tissues and HS specimens from different patients were examined.Autophagy inducers and inhibitors were used to cure established HS in rabbit ears,and the expression of Beclin-1,p62,and LC3II at the RNA and protein level was determined.Lastly,the effects of autophagy inducers and inhibitors on HS development were analyzed.Results:Compared to normal skin tissues,the expression of LC3II and Beclin-1 was higher(P<0.05),while that of p62 was lower(P<0.05)in HS tissues.In addition,the LC3II/LC3I ratio was increased during HS formation,and the altered expression of the three proteins stabilized after one year.Administration of autophagy inducers enhanced the formation of HS as well as the expression levels of LC3II and Beclin-1 but decreased p62 expression.Meanwhile,administration of autophagy inhibitors increased the expression of LC3II,Beclin-1,and p62,along with reduced HS formation.Conclusion:Autophagic activity increased during HS initiation and subsequent stabilization.In addition,autophagy inhibitors were able to inhibit HS formation by suppressing autophagy,whereas autophagy inducers promoted scar hyperplasia by enhancing autophagy。

A modified scar model with controlled tension on secondary wound healing in mice

Pathological scars might cause a distorted appearance and restricted mobility,and the study of scar pathophysiology has been hindered by the absence of a reliable model.In this study,we introduce a model with a modified device to induce controlled tension on a wound healing by secondary intention to overcome the shortcomings of the model generated by Aarabi et al.We investigated and recommend an induction of 0.1 N/mm^(2) tension on day 7 for 14 days to mimic the characteristics of human scars.A 3.5-fold increase in scar tissue and a 2-fold increase in collagen production were induced by the modified model.Histologically,the modified method increased scar thickness.However,no significant difference was found in cell density between the two groups.This modified procedure significantly increased scar tissue,which could be used for further cellular and biomolecular research.The mechanical force applied to the wound became measurable and controllable.This method is more convenient for researchers to observe in realtime and for providing timely adjustments of the tension used in this modified model.

Modeling human hypertrophic scars with 3D preformed cellular aggregates bioprinting

The therapeutic interventions of human hypertrophic scars(HHS)remain puzzle largely due to the lack of accepted models.Current HHS models are limited by their inability to mimic native scar architecture and associated pathological microenvironments.Here,we create a 3D functional HHS model by preformed cellular aggregates(PCA)bioprinting,firstly developing bioink from scar decellularized extracellular matrix(ECM)and alginate-gelatin(Alg-Gel)hydrogel with suitable physical properties to mimic the microenvironmental factors,then pre-culturing patient-derived fibroblasts in this bioink to preform the topographic cellular aggregates for sequent printing.We confirm the cell aggregates preformed in bioink displayed well defined aligned structure and formed functional scar tissue self-organization after bioprinting,hence showing the potential of creating HHS models.Notably,these HHS models exhibit characteristics of early-stage HHS in gene and protein expression,which significantly activated signaling pathway related to inflammation and cell proliferation,and recapitulate in vivo tissue dynamics of scar forming.We also use the in vitro and in vivo models to define the clinically observed effects to treatment with concurrent anti-scarring drugs,and the data show that it can be used to evaluate the potential therapeutic target for drug testing.The ideal humanized scar models we present should prove useful for studying critical mechanisms underlying HHS and to rapidly test new drug targets and develop patient-specific optimal therapeutic strategies in the future.