Targeted gene silencing of TLR4 using liposomal nanoparticles for preventing liver ischemia reperfusion injury

RNAi-based therapy is a promising strategy for the prevention of ischemia-reperfusion injury (IRI). However, systemic administration of small interfering RNA (siRNA) may cause globally nonspecific targeting of all tissues, which impedes clinical use. Here we report a hepatocyte-specific delivery system for the treatment of liver IRI, using galactose-conjugated liposome nanoparticles (Gal-LipoNP). Heptocyte-specific targeting was validated by selective in vivo delivery as observed by increased Gal-LipoNP accumulation and gene silencing in the liver. Gal-LipoNP TLR4 siRNA treatment resulted in a significant decrease of serum alanine transferase (ALT) and aspartate transaminase (AST) in a hepatic IRI model. Histopathology displayed an overall reduction of the injury area in the Gal-LipoNP TLR4 siRNA treated mice. Additionally, neutrophil accumulation and lipid peroxidase-mediated tissue injury, detected by MPO, MDA and ROS respectively, were attenuated after Gal-LipoNP TLR4 siRNA treatment. Moreover, therapeutic effects of Gal-LipoNP TLR4 siRNA were associated with suppression of the inflammatory cytokines IL-1 and TNF-α. Taken together, this study is the first demonstration of liver IRI treatment using liver-specific siRNA delivery.

Outstanding survival and regeneration process by the use of intelligent acellular dermal matrices and mesenchymal stem cells in a burn pig model

A pig model with a deep large burn was used to study the regeneration process induced by mesenchymal stem cells (MSCs) and acellular pig dermal matrices, made intelligent by the combination with biodegradable nanofibers loaded with growth factors (granulocyte-macrophage colony-stimulating factor and epidermal growth factor) and coated with the anti-CD44 monoclonal antibody (intelligent acellular dermal matrices, IADMs). These IADMs are specially designed to integrate in the wound bed as new biological scaffolds as well as to specifically recruit and attach circulating and/or externally applied MSCs through the anti-CD44 antibody while delivering precise amounts of growth factors. In this way, the reparative process as well as the aesthetic and functional results were enhanced in our burn model. The animal survived, the wound was completely closed, and total regeneration of the skin was obtained without much scarring. Surprisingly, hair follicles and other skin appendages developed despite the severity and deepness of the burn. Even burned muscles and ribs seemed to have undergone a regenerative process by the end of the study. Based on these findings, we have proposed the use of IADMs and autologous, allogeneic or xenogeneic MSCs, as a new paradigm for the future treatment of large burns and probably other dermatological and cosmetic human conditions.

The next generation of burns treatment: intelligent films and matrix, controlled enzymatic debridement, and adult stem cells

We describe a novel technology based on nanoengineered multifunctional acellular biologic scaffolds combined with wound dressings and films of the same kind. This method allows selective delivery and release of shielded biomaterials and bioactive substances to a desired wound or damaged tissue while stimulating the selective anchoring and adhesion of endogenous circulating repairing cells, such as mesenchymal stem cells, to obtain a faster and more physiologic healing process. We also present a new controlled enzymatic debridement process for more effective burned tissue scarolysis. In light of our preliminary in vitro and in vivo data, we are convinced that these approaches can include the use of other kinds of adult stem cells, such as endometrial regenerative cells, to improve the vascularization of the constructs, with great potential in the entire tissue and organ regeneration field but especially for the treatment of severely burned patients, changing the way these lesions may be treated in the future.