Experimental Study Of Three-Dimensional Degradable Mesh Scaffolds Assisted Fat Transplantation For Breast Reconstruction

BackgroundAs a less invasive approach,autologous fat transplantation is called the third alternative of breast reconstruction.However,due to the narrow space of local subcutaneous after mastectomy,it is not easy to retain the volume of fat-transplanted alone.Recently,tissue-engineered scaffolds assistting fat transplantation has become a new focus.Some studies have shown that three-dimensional mesh scaffolds can improve the survival rate of transplanted fat,while the incidence of complications such as oil sac is low.However,the specific mechanism is still unclear.In addition,there still has some aspects that can be improved in the existing studies:1.Most of the existing studies are single implantation of large-volume scaffolds,which requires a large incision during implantation and has a large trauma;2.The scaffolds used in some studies are not degradable,which will cause continuous foreign body stimulation and is not conducive to the survival and regeneration of the transplanted fat.Therefore,the aim of this study is to explore the effect of small volume three-dimensional degradable mesh scaffolds in assisting fat transplantation in nude mice model,and explore the specific mechanism of how it improve the survival and regeneration.The view of this study is to realize the combination of small volume degradable scaffolds and transplanted fat into "fat-scaffold transplantation unit" in the future--personalized filling can be carried out according to the number of units with different soft tissue defects through minimally invasive incision.Methods and results1.The effect of three-dimensional degradable mesh scaffolds in assisting fat transplantation.The experiment was carried out with a small volume three-dimensional degradable mesh scaffolds made of L-polylactic acid(PLLA)material with excellent biological safety via 3D printing.The experimental models were divided into two groups:Three-dimensional mesh scaffolds(TDAMS)group and control group:In the TDAMS group,the mesh scaffold was placed subcutaneously through a small incision,followed by fat transplanted into the scaffold;The control group received equal amount of fat transplantation.Grafts were harvested at the 1st,4th,8th and 12th weeks after fat transplantation.The two groups were analyzed and compared by gross observation and volume retention analysis,HE staining,immunofluorescence staining and Masson staining.Results:At the 12th week after transplantation,the volume retention rate of TDAMS group was significantly higher than that of the control group(63.33%±10.80%and 34.17%± 13.93%,respectively)(P<0.05).HE and immunofluorescence results showed that at the 4th week,a large number of oil sacs were formed in the control group,while there was significant angiogenesis in the TDAMS group.2.Exploring the specific mechanism of three-dimensional degradable mesh scaffolds to improve the survival rate of transplanted fat.The expression of vascular growth factors(VEGF,PDGF and BFGE)was detected by qPCR at the 1st,4th,8th and 12th week after transplantation;Human umbilical vein endothelial cells(HUVEC)were labeled with Dil to analyze the migration of HUVEC in vivo;Scratch experiment was carried out in vitro by using cell stress culture plates with different basal stiffness.Results:qPCR showed that the expression of VEGF,PDGF and BFGE in TDAMS group was significantly higher than that in control group at 1-12 weeks after transplantation,and VEGF and PDGF reached their peak at the 4th week.In vivo migration experiment showed that HUVEC began to migrate to the transplanted fat at 3 days after transplantation,and more cells migrated in TDAMS group.In vitro scratch experiment showed that the migration rate of endothelial cells was significantly higher than 2.0Kpa and 0.1 Kpa when the basal stiffness was 3Kpa(P<0.001)Conclusions1.Small volume three-dimensional degradable mesh scaffolds can promote the expression of vascular growth factors(VEGF,PDGF and BFGF)in the early stage of fat transplantation,improve the long-term retention rate of fat transplantation,and reduce the occurrence of oil sacs after transplantation.2.The specific mechanism of small volume three-dimensional degradable mesh scaffolds to improve the survival rate of transplanted fat may be that it can further promote the early angiogenesis of transplanted fat by increasing the stiffness of transplanted fat,driving the migration of endothelial cells and improving the expression of vascular growth factor.