Title : Lipid nanoparticle-encapsulated VEGFa siRNA facilitates cartilage formation by suppressing angiogenesis
Abstract:
Cartilage reconstruction in plastic and reconstructive surgery is mostly realized by surgical placement of supports, such as autologous rib cartilage implantation and prosthetic material implantation in rhinoplasty and microtia, but there are problems such as limited autologous cartilage sources and prosthesis rejection and exposure. Therefore, finding a clinically applicable prosthetic source with no or reduced damage to healthy tissue is important for cartilage regeneration. Adipose-derived stem cells (ADSC), which have excellent self-renewal, proliferative, and immunomodulatory abilities and maintain their chondrogenic potential after multiple proliferations, can be easily obtained in large quantities by minimally invasive liposuction, bringing new hope for the creation of bioengineered craniofacial cartilage. However, subcutaneous vascular invasion leads to tissue mineralization and ossification, which is not conducive to stem cell-based cartilage regeneration.
In this paper, a novel tissue-engineered bionic scaffold was constructed using adipose stem cells in combination with GelMA hydrogel. To inhibit the infiltration of the local vascular system, we incorporated VEGFa siRNA, and optimized cationic lipid nanoparticles (LNPs) were prepared by microfluidic self-assembly technology for efficient delivery of VEGFa siRNA. The stem cell scaffolds were implanted subcutaneously in nude mice, and vascular infiltration and cartilage regeneration were observed after 8 weeks.
The results showed that we successfully fabricated LNPs, a non-toxic, safe, and efficient delivery vector, which exhibited good transfection and endosomal escape ability.VEGFa siRNA-LNPs could successfully down-regulate VEGFa expression in vitro. The results of implanting hydrogel-cell-VEGFa siRNA-LNPs scaffolds into the subcutaneous of nude mice showed that we successfully achieved cartilage regeneration in a subcutaneous environment. The newborn cartilage tissue was superior, not only had more cartilage extracellular matrix, but also cartilage-associated markers SOX9 as well as COL-II and Acan were significantly upregulated. This was attributed to the inhibition of angiogenesis by VEGFa siRNA, which creates a localized environment of hypoxia and lack of nutrient supply, and aids in cartilage regeneration by upregulating HIF-1α and FOXO in the cells.
In conclusion, we constructed a hydrogel-cell- VEGFa siRNA -LNPs scaffold that achieved superior cartilage regeneration. This is a very promising cartilage regeneration strategy to break through the bottleneck of prosthetic materials for clinical microtia and rhinoplasty, and it is an innovative attempt for clinical translation of stem cells, which provides a theoretical basis for the investment of large-scale research before clinical application.
