Soluble CD54 induces human endothelial cells ex vivo expansion useful for cardiovascular regeneration and tissue engineering application

Aim

Consistent expansion of primary human endothelial cells in vitro is critical in the development of engineered tissue. A variety of complex culture media and techniques developed from different basal media have been reported with alternate success. Incongruous results are further confounded by donor-to-donor variability and cellular source of derivation. Our results demonstrate how to overcome these limitations using soluble CD54 (sCD54) as additive to conventional culture medium.

Methods and results

Isolated primary fragment of different vessel types was expanded in Ham's F12 DMEM, enriched with growth factors, Fetal Calf Serum and conditioned medium of Human Umbilical Vein Endothelial Cells (HUVEC) collected at different passages. Cytokine content of culture media was analyzed in order to identify the soluble factors correlating with better proliferation profile. sCD54 was found to induce the in vitro expansion of human endothelial cells (HECs) independently from the vessels source and even in the absence of HUVEC-conditioned medium. The HECs cultivated in the presence of sCD54 (50 ng/ml), resulted positive for the expression of CD146 and negative for CD45, and lower fibroblast contamination. Cells were capable to proliferate with an S phase of 25%, to produce vascular endothelial growth factor, VEGF, (10 ng/ml) and to give origin to vessel-like tubule in vitro.

Conclusion

Our results demonstrate that sCD54 is an essential factor for the in-vitro expansion of HECs without donor and vessel-source variability. Resulting primary cultures can be useful, for tissue engineering in regenerative medicine (e.g. artificial micro tissue generation, coating artificial heart valve etc.) and bio-nanotechnology applications.

A new clinical approach: use of blood-derived stem cells (BDSCs) for superficial digital flexor tendon injuries in horses

AIMS

In this study, we present an innovative therapy using stem cells that were obtained from the peripheral blood of racehorses affected by uninduced superficial digital flexor tendon (SDFT) injuries.

MAIN METHODS

Blood-derived stem cells (BDSCs) were generated from the blood samples of three horses in the presence of macrophage colony-stimulating factor (M-CSF). The racehorses received a single autologous BDSC treatment, which resulted in the successful repair of the tendons injuries.

KEY FINDINGS

The results demonstrated that the BDSCs injection into the damaged tendon stimulated the regeneration of normal tissue. Furthermore, a relationship may exist between the speed and the quality of new tissue formation and the welfare and management of the treated animals.

SIGNIFICANCE

This study demonstrates that stem cell technology offers new tools for tissue repair that in many cases is considered incurable, and provides additional evidence that BDScs injections increase the speed and quality of the regeneration process in different animal tissues.

Dendritic cells shuttle microbes across gut epithelial monolayers

Understanding the mechanisms governing the type of induced immune response after microbial invasion, could be of crucial importance for the rational design of a bacteria-based vaccine. Targeting a vaccine directly to dendritic cells (DCs), which are considered the most powerful antigen presenting cells, could be extremely effective. Here we describe that CD11b+CD8alpha- dendritic cells are involved in the direct bacterial uptake across mucosal surfaces. DCs are widely spread in the lamina propria of the gut and are recruited at the site of infection. DCs open the tight junctions between epithelial cells, send dendrites outside of the epithelium and sample bacteria. Moreover, the integrity of the epithelial barrier is preserved because DCs express tight junction proteins, such as occludin, claudin 1 and Junctional Adhesion Molecule (JAM) and can establish tight junctions-like structures with neighbouring epithelial cells.

Dendritic cells express tight junction proteins and penetrate gut epithelial monolayers to sample bacteria

Penetration of the gut mucosa by pathogens expressing invasion genes is believed to occur mainly through specialized epithelial cells, called M cells, that are located in Peyer's patches. However, Salmonella typhimurium that are deficient in invasion genes encoded by Salmonella pathogenicity island 1 (SPI1) are still able to reach the spleen after oral administration. This suggests the existence of an alternative route for bacterial invasion, one that is independent of M cells. We report here a new mechanism for bacterial uptake in the mucosa tissues that is mediated by dendritic cells (DCs). DCs open the tight junctions between epithelial cells, send dendrites outside the epithelium and directly sample bacteria. In addition, because DCs express tight-junction proteins such as occludin, claudin 1 and zonula occludens 1, the integrity of the epithelial barrier is preserved.