Current status of animal-to-human transplantation

Osteogenic Differentiation of Periodontal Ligament Stem Cells Seeded on Equine-Derived Xenograft in Osteogenic Growth Media

Background and Objectives: The duration of bone turnover is critical, and different time points help in identifying the optimal endpoint of treatment duration. However, investigating the combination of xenograft and stem cells to allow tissue regeneration within an ideal time duration remains an under-investigated topic. The current study aimed to assess the impact of equine-derived xenograft bone blocks in assisting the human periodontal ligament stem cells (PDLSCs) to demonstrate osteogenic differentiation (collagen type 1 expression and calcium deposition) within an osteogenic growth media. Materials and Methods: Human PDLSCs were acquired commercially and seeded onto xenograft bone blocks. After the 14th and 21st day of culture, enzyme-linked immunoassay (ELISA) was utilized for the detection and quantification of levels of collagen type I, while the mineralization assessment (deposition of calcium) was conducted by staining the PDLSCs with Alizarin Red S (ARS). The statistical comparison between the means and standard deviations of study groups were evaluated using analysis of variance (ANOVA). Results: ELISA assessment revealed an upsurge in the expression of collagen type I for PDLSCs cultured with xenograft after 14 and 21 days compared to the controls (intergroup comparisons significant at p < 0.05). Similar findings were obtained for mineralization assessment and on ARS staining. PDLSCs cultured with xenograft bone blocks presented an increased deposition of calcium compared to their control counterparts (intergroup comparisons significant at p < 0.05). Conclusions: PDLSCs embedded in xenograft bone blocks inside an osteogenic growth medium demonstrated greater osteogenic differentiation potential after 14 and 21 days. This superior osteogenic differentiation capability was evident by increased collagen type I expression and more significant calcium deposition at the 14th and 21st days after culture.

The 3D Bioprinted Scaffolds for Wound Healing

Skin tissue engineering and regeneration aim at repairing defective skin injuries and progress in wound healing. Until now, even though several developments are made in this field, it is still challenging to face the complexity of the tissue with current methods of fabrication. In this review, short, state-of-the-art on developments made in skin tissue engineering using 3D bioprinting as a new tool are described. The current bioprinting methods and a summary of bioink formulations, parameters, and properties are discussed. Finally, a representative number of examples and advances made in the field together with limitations and future needs are provided.

Bone Grafts, Bone Substitutes and Regenerative Medicine Acceptance for the Management of Bone Defects Among French Population: Issues about Ethics, Religion or Fear?

Several techniques exist to manage bone defects in patients: bone grafts (autograft, allograft, xenograft), use of synthetic bone substitutes, or use of the products of bone regenerative medicine. Studies generally focus on their efficacy, but few focus on their acceptance. Our objectives were to assess their theoretical acceptance among the French general population, and to identify issues justifying refusals, by mean of an open e-questionnaire. The questionnaire was submitted to a general French population, and explained these techniques in an understandable way. Participants were asked to say whether they would accept or refuse these techniques, specifying why in case of refusal (fear of the technique, ethical reasons, religious reasons). In total, 562 persons participated. Autograft and use of the products of bone regenerative medicine were the most accepted techniques (93.4% and 94.1%, respectively). Xenograft was the least accepted technique (58.2%). Most refusals were due to fear such as failure, pain, infection (autograft 8%, allograft 14.9%, xenograft 25.3%, synthetic bone substitutes 14.6%, and products of bone regenerative medicine 6.8%). Ethical reasons were mostly mentioned for allograft (6.4%) and xenograft (18.3%). Religious reasons were scarcely mentioned, only for xenograft (1.2%). Thus, acceptance of techniques does not seem to be greatly linked to sociodemographic characteristics in France. However, other countries with their own cultural, religious, and population patterns may show different levels of acceptance. This study shows that bone regenerative medicine is a promising research direction, reaching biological and also humanist quality standards, expected to improve the health of patients. Information is still the cornerstone to defuse issues about fear.

Degradation Effect of Diepoxide Fixation on Porcine Endogenous Retrovirus DNA in Heart Valves: Molecular Aspects

Purpose

Xenotransplantations of porcine cells, tissues, and organs involve a risk of zoonotic viral infections in recipients, including by porcine endogenous retroviruses (PERVs), which are embedded the genome of all pigs. An appropriate preparation of porcine heart valves for transplantation can prevent retroviral infection. Therefore, the present study focuses on the effect of epoxy compounds and glutaraldehyde on the PERV presence in porcine heart valves prepared for clinical use.

Methods

Porcine aortic heart valves were fixed with ethylene glycol diglycidyl ether (EDGE) at 5°C and 25°C as well as with glutaraldehyde (GA) for 4 weeks. Salting out was used to isolate genomic DNA from native as well as EDGE- and GA-fixed fragments of valves every week. Quantification of PERV-A, PERV-B, and PERV-C DNA was performed by real-time quantitative polymerase chain reaction (QPCR).

Results

All subtypes of PERVs were detected in native porcine aortic heart valves. The reduction of the PERV-A, PERV-B, and PERV-C DNA copy numbers was observed in the heart valves which were EDGE-fixed at both temperatures, and in GA-fixed ones in the following weeks. After 7 and 14 days of EDGE cross-linking, significant differences between the investigated temperatures were found for the number of PERV-A and PERV-B copies. PERV DNA was completely degraded within the first week of EDGE fixation at 25°C.

Conclusions

EDGE fixation induces complete PERV genetic material degradation in porcine aortic heart valves. This suggests that epoxy compounds may be alternatively used in the preparation of bioprosthetic heart valves in future.