PRP-fibrinogen gel-like chondrocyte carrier stabilized by TXA-preliminary study.

Three dimensional scaffolds are becoming increasingly popular in the treatment of cartilage defects. Platelet-rich plasma (PRP) and fibrinogen can be used potentially as a three dimensional cell delivery vehicle. PRP is a fraction of plasma containing high levels of growth factors such as PDGF, IGF-I and TGF-I, which stimulate chondrocyte to synthesize extracellular matrix. The aim of this study was to prepare grafts based on fibrinogen, and PRP with fibrinogen as a chondrocyte carrier. Another goal was to estimate tranexamic acid as an antifibrynolytic agent in chondrocyte grafts and in monolayer culture for about 3 weeks. 450 ml blood was collected to produce fibrinogen and PRP from a Regional Blood Center voluntary donor. To prepare gel grafts, chondrocytes were mixed with PRP and, fibrinogen and then with thrombin in calcium chloride. Different doses of tranexamic acid or aprotinin were used to stabilize the constructs. Grafts were cultivated for 4 weeks in vitro to evaluate and compare their disintegration. Grafts were stable for the entire observation period and revealed no shrinkage. During graft storage, cells appeared to be viable, and cell migration from the graft to the culture plate was observed. Chondrocyte graft preparation based on PRP and fibrinogen is a promising method. PRP-fibrinogen carrier in combination with cells constitutes highly plastic and adhesive grafts. Tranexamic acid can be used as an anti-fibrinolytic agent in chondrocyte graft preparation instead of aprotinin.

Results of the clinical donor case and quality system case workshops of the European Association of Tissue Banks annual meeting 2009.

The European Association of Tissue Banks (EATB) Donor Case Workshop and Quality System Case workshop are forums held within the program of the EATB Annual Congress. These workshops offer an opportunity to discuss and evaluate approaches taken to challenging situations, regarding donor selection and quality issues, and strengthen the professional tissue banking and regulatory networks across Europe. This report reflects some of the discussion at the congress workshops and also subsequent correspondence between the various individuals who submitted cases for discussion. The cases presented to the workshops demonstrate that the findings, their interpretation, deducted actions and preventive measures in tissue banks are not predictable. The varied responses and lack of consensus corroborate this and clearly indicate that operating procedures cannot comprehensively cover or prepare for all eventualities. For many of the issues raised there is a lack of information in the published literature. The workshops actively engage participants, representing a wide array of international expertise, in an informal, secure and enjoyable setting, which facilitates learning from peers and provides potential solutions to those submitting cases. By publishing a summary of the discussions, we hope to reach a wider audience and to stimulate individuals to undertake full literature reviews or research on some of the discussed subjects.

Liposome-based DNA carriers may induce cellular stress response and change gene expression pattern in transfected cells.

BACKGROUND: During functional studies on the rat stress-inducible Hspa1b (hsp70.1) gene we noticed that some liposome-based DNA carriers, which are used for transfection, induce its promoter activity. This observation concerned commercial liposome formulations (LA), Lipofectin and Lipofectamine 2000. This work was aimed to understand better the mechanism of this phenomenon and its potential biological and practical consequences. RESULTS: We found that a reporter gene driven by Hspa1b promoter is activated both in the case of transient transfections and in the stably transfected cells treated with LA. Using several deletion clones containing different fragments of Hspa1b promoter, we found that the regulatory elements responsible for most efficient LA-driven inducibility were located between nucleotides -269 and +85, relative to the transcription start site. Further studies showed that the induction mechanism was independent of the classical HSE-HSF interaction that is responsible for gene activation during heat stress. Using DNA microarrays we also detected significant activation of the endogenous Hspa1b gene in cells treated with Lipofectamine 2000. Several other stress genes were also induced, along with numerous genes involved in cellular metabolism, cell cycle control and pro-apoptotic pathways. CONCLUSIONS: Our observations suggest that i) some cationic liposomes may not be suitable for functional studies on hsp promoters, ii) lipofection may cause unintended changes in global gene expression in the transfected cells.