Gene therapy--its potential in surgery

Lipid-based Nanocarriers for siRNA Delivery: Challenges, Strategies and the Lessons Learned from the DODAX: MO Liposomal System

The possibility of using the RNA interference (RNAi) mechanisms in gene therapy was one of the scientific breakthroughs of the last century. Despite the extraordinary therapeutic potential of this approach, the need for an efficient gene carrier is hampering the translation of the RNAi technology to the clinical setting. Although a diversity of nanocarriers has been described, liposomes continue to be one of the most attractive siRNA vehicles due to their relatively low toxicity, facilitated siRNA complexation, high transfection efficiency and enhanced pharmacokinetic properties. This review focuses on RNAi as a therapeutic approach, the challenges to its application, namely the nucleic acids' delivery process, and current strategies to improve therapeutic efficacy. Additionally, lipid-based nanocarriers are described, and lessons learned from the relation between biophysical properties and biological performance of the dioctadecyldimethylammonium:monoolein (DODAX: MO) system are explored. Liposomes show great potential as siRNA delivery systems, being safe nanocarriers to protect nucleic acids in circulation, extend their half-life time, target specific cells and reduce off-target effects. Nevertheless, several issues related to delivery must be overcome before RNAi therapies reach their full potential, namely target-cell specificity and endosomal escape. Understanding the relationship between biophysical properties and biological performance is an essential step in the gene therapy field.

Gene therapy in transplantation

Gene therapy is an exciting and novel technology that offers the prospect of improving transplant outcomes beyond those achievable with current clinical protocols. This review explores both the candidate genes and ways in which they have been deployed to overcome both immune and non-immune barriers to transplantation success in experimental models. Finally, the major obstacles to implementing gene therapy in the clinic are considered.

Overexpression of indoleamine dioxygenase in rat liver allografts using a high-efficiency adeno-associated virus vector does not prevent acute rejection

The aim of this study was to evaluate the ability of local overexpression of indoleamine dioxygenase (IDO) to abrogate rat liver transplant rejection by the use of an adeno-associated virus vector [recombinant adeno-associated virus 2/8 (rAAV2/8)] to deliver the transgene to the allograft prior to transplantation. A green fluorescent protein (GFP)-expressing vector [recombinant adeno-associated virus 2/8-liver-specific promoter 1-enhanced green fluorescent protein (rAAV2/8-LSP1-eGFP)] was used to examine the kinetics of expression and optimal dosing for transduction of Piebald Virol Glaxo (PVG) rat livers. A vector encoding the rat IDO gene (rAAV2/8-LSP1-rIDO) was constructed and tested by its ability to induce tryptophan catabolism and kynurenine production in vitro and in vivo. PVG donor rats were injected, via the portal vein, with rAAV2/8-LSP1-rIDO 2 weeks before transplantation into PVG strain isograft or Lewis (LEW) strain allograft recipients. With the enhanced GFP vector, 29.5% and 47.4% of hepatocytes were found to express GFP at 3 and 6 weeks after injection, respectively. In untransplanted PVG animals, the rAAV2/8-LSP1-rIDO vector induced, 3 weeks after administration, a 1.8-fold increase (P = 0.0161) in liver IDO activity, which was associated with a fall in serum tryptophan to 0.5 times the baseline level (P < 0.001). PVG recipients of PVG liver isografts pretreated with the IDO-expressing vector had a 45% lower level of serum tryptophan than recipients of isografts pretreated with the GFP-expressing vector (P = 0.03). LEW recipients of PVG liver allografts pretreated with the rat IDO vector had a median survival time of 12 days, whereas recipients of allografts pretreated with rAAV2/8-LSP1-eGFP had a median survival time of 13 days (P = 0.38). Both groups displayed similar histological features of acute cellular rejection. In conclusion, rAAV2/8 vectors produce highly efficient, though delayed, hepatocyte transduction in vivo and provide a useful gene delivery tool for transplantation models. However, gene delivery using IDO was unsuccessful in prolonging rat liver allograft survival.

[Pathogenesis of chronic wounds]

Chronic, nonhealing wounds and their therapy are not only a medical problem but a severe economic one as well. Such wounds have a great effect on quality of life. Basic research has enhanced our understanding of the stimulation and inhibition of wound healing and provides the basis for introducing new and innovative treatment methods. This paper reviews the most relevant in- and extrinsic factors that disturb physiologic wound healing to result in chronic nonhealing wounds. In addition, molecular intervention modalities targeting various aspects of wound repair are demonstrated.

Plastische Deckung von Weichteildefekten im Gesicht

The difficulties in facial reconstruction derive from the unique character of the face and the availability of local matching tissues. Facial reconstructive surgery must aim at a functionally and aesthetically rehabilitated patient. The performance of facial plastic surgery requires an understanding and the application of many important principles. The aim of this paper is to review the critical factors to be considered in the management of surgical wounds by second-intention healing, primary closure, skin grafting, and repair with local or distant free flaps. The key concepts useful in flap choice and implementation are discussed. In addition, an overview of new developments in tissue engineering and gene therapy as they relate to facial plastic surgery is provided.

Interleukin-10 modified dendritic cells induce allo-hyporesponsiveness and prolong small intestine allograft survival

AIM: To investigate whether IL-10-transduced dendritic cells (DCs) could induce tolerogenicity and prolong allograft survival in rat intestinal transplantation.

METHODS: Spleen-derived DCs were prepared and genetically modified by hIL-10 gene. The level of IL-10 expression was quantitated by ELISA. DC function was assessed by MTT in mixed leukocyte reaction. Allogeneic T-cell apoptosis was examined by flow cytometric analysis. Seven days before heterotopic intestinal transplantation, 2 × 10⁶ donor-derived IL-10-DC were injected intravenously, then transplantation was performed between SD donor and Wistar recipient.

RESULTS: Compared with untransduced DC, IL-10-DC could suppress allogeneic mixed leukocyte reaction (MLR). The inhibitory effect was the most striking with the stimulator/effector (S/E) ratio of 1:10. The inhibition rate was 33.25%, 41.19% (P < 0.01) and 22.92% with the S/E ratio of 1:1, 1:10 and 1:50 respectively. At 48 h and 72 h by flow cytometry counting, apoptotic T cells responded to IL-10-DC in MLR were 13.8% and 30.1%, while untransduced group did not undergo significant apoptosis (P < 0.05). IL-10-DC pretreated recipients had a moderate survival prolongation with a mean allograft survival of 19.8 d (P < 0.01), compared with 7.3 ± 2.4 d in control group and 8.3 ± 2.9 d in untransduced DC group. Rejection occurred in the control group within three days. The difference between untreated DC group and control group was not significant.

CONCLUSION: IL-10-DC can induce allogenic T-cell hyporesponsiveness in vitro and apoptosis may be involved in it. IL-10-DC pretreatment can prolong intestinal allograft survival in the recipient.