Human heart valve homografts, usually donated after death, are banked worldwide to facilitate reconstructive cardiac surgery, which is a necessary procedure to repair both congenital and acquired cardiac defects. Donations of substances of human origin carry a risk of transmitting infection to recipients. As a result, several different precautions are taken to minimise this risk. Testing the tissue product for possible contamination, and carrying out decontamination of the tissue (often through the use of an antibiotic cocktail) are two of the procedures performed routinely in tissue establishments to minimize the risk of transplantation associated infections. This area of clinical practice does not have an established external quality assessment (EQA) Scheme. This report describes an initial pilot scheme of an EQA to investigate the microbiology testing of heart tissue banking, a collaboration between the Scottish National Blood Transfusion Service (SNBTS) and UK National External Quality Assessment Service (UK NEQAS) for Microbiology. The results highlight the differences in practice between different tissue banks, further supporting the need for setting up an EQA on a regular basis and the need to produce a best practice method document to attempt harmonisation of the testing.

Burn injuries in children are a critical public health issue with significant mortality and morbidity. Allogeneic skin grafts, both cadaveric and freshly donated, have been utilized in pediatric burn care since many years, yet their efficacy and safety remain to be systematically assessed. This systematic review (PROSPERO number: CRD42024560654) analyzed studies from 01/2000 to 07/2024 sourced from PubMed. Inclusion criteria targeted RCTs and retrospective studies focused on the use of allogeneic skin grafts in pediatric burn patients. Extracted data were presented in a narrative synthesis and a comprehensive table. Established tools were used for risk of bias assessment. 13 studies were deemed suitable for analysis, with only two qualifying as RCTs. Allogeneic skin grafts have shown promise in managing pediatric burns, especially in resource-limited settings where autografts or skin substitutes are not available. Studies varied in their treatment approaches, with allogeneic grafts often used for more severe burns, suggesting that observed adverse effects may be due to injury severity rather than treatment type. The retrospective nature of the majority suggests a limited level of evidence. Moreover, the heterogeneity among study designs and patient populations makes it difficult to draw definitive conclusions. Allogeneic skin grafts represent a valuable treatment option in pediatric burn care. However, further well-designed RCTs are essential to establish a stronger evidence base for their use and to guide clinical decision-making. The current literature underscores the potential of allogeneic grafts but also the necessity for more nuanced research tailored to pediatric needs.

Interactions between MSCs and cancer cells are complex and multifaceted and have been shown to exhibit both pro-tumor and antitumor effects. This study investigated the effects of conditioned medium (CM) and cell extract (CE) from two different ERα statuses, MCF-7 and MDA-MB-231 breast cancer cell lines, on adipose-derived mesenchymal stem cells (ASCs). Findings showed that CM and CE increased cellular metabolic activity and viability of ASCs, upregulated angiogenic factors VEGF and HIF-1α, and cytokine TGF-β expression levels. However, CM and CE treatment did not significantly affect the clonogenicity of ASCs. In addition, apoptosis-related genes caspase-3 and 9 showed differential expression patterns among the treatment groups. The findings suggest that breast cancer cell-derived factors can modulate the behavior of ASCs, highlighting their potential as a therapeutic tool in breast cancer treatment and tissue regeneration. However, it is essential to consider the potential risks associated with CM and CE treatment on ASCs, as well as the potential recruitment of ASCs by cancer tumors and the risks associated with this recruitment. Further research is needed to elucidate these potential risks and benefits.

Tissue engineering and cartilage transplantation constitute an evolving field in the treatment of osteoarthritis, with therapeutic and clinical promise shown in autologous chondrocyte implantation. The aim of this systematic review is to explore current clinical trials that utilized autologous chondrocyte transplantation (ACT) and assess its efficacy in the treatment of osteoarthritis. PubMed, Ovid MEDLINE, and Google-Scholar (pages 1-20) were searched up until February 2023. Inclusion criteria consisted of clinical trials that involve autologous cartilage transplantation for the treatment of osteoarthritis. Clinical, imaging, arthroscopic, and histologic outcomes were assessed. A total of 15 clinical trials, involving 851 participants, were included in the study. All trials utilized ACT in the treatment of knee osteoarthritis through varying scaffolds: collagen-based (10 trials), polymer-based (2 trials), hyaluronic-acid based (2 trials), and spheroid technology (1 trial). Clinical improvement of patients undergoing ACT was noted in 14 trials; five showed superior clinical outcomes compared to the control group, while one showed inferiority compared to mesenchymal stem cells. Postoperative imaging was utilized to assess the degree of cartilage regeneration in 11 trials. Ten trials showed signs of cartilage recovery with ACT, four trials showed no difference, and two showed worse outcomes when compared to controls. Second-look-arthroscopy was performed in three trials, which reported varying degrees of improvement in cartilage regeneration. Histologic analysis was performed in four trials and generally showed promising results. While improved clinical outcomes were demonstrated, conflicting findings in postoperative outcome analysis raise questions about the unequivocal utility of ACT. Additional research with control groups, randomization, and appropriate blinding is required.

Amniotic membrane is arguably one of the most popular biological wound dressings on the market today. Various growth factors and cytokines inherent to amniotic membrane tissue have been recognized as key mediators in wound healing and tissue regeneration, giving the tissue its clinical utility. Sterilization methodologies using irradiation are recognized as the gold standard in the field and routinely used to prepare tissue allografts, including amniotic membrane for transplantation. However, irradiation is not always compatible in preserving the physical structure or biochemical factors of biological materials and can potentially result in detrimental effects to the critical quality attributes of allograft tissues. Alternatively, a novel sterilization technique involving supercritical carbon dioxide (SCCO2) has been shown to have minimal effect on the inherent biophysical properties of sensitive biological tissues and tissue-derived products. At BioBridge Global, we have developed a process utilizing SCCO2 technology for the sterilization of an amniotic membrane tissue allograft product. This process, first and foremost, meets industry standards for sterilization while simultaneously maintaining the biochemical composition of the tissue. Our results show that upon SCCO2 sterilization, most of the growth factors tested were conserved, with many at quantities significantly greater than commercially available gamma and electron beam irradiated tissue. The SCCO2-sterilized amniotic membrane allograft is unique in that it is designed to overcome limitations associated with traditional tissue sterilization methodologies, namely, the conservation of key biological factors inherent to native amniotic membrane tissue. It is anticipated that by retaining these biological factors, clinical outcomes associated with the use of SCCO2-sterilized amniotic membrane will be improved.

Non-healing wounds cost the National Health Service over £5.6 billion annually in wound management. Skin allografts are used to treat non-healing wounds, ulcers and burns, offering the best protection against infection. In order to allow host cells to repopulate and to avoid immunogenicity, cell components are removed through decellularisation. Decellularisation of human dermis has so far been performed in NHS Blood and Transplant using a combination of two enzymes (RNase T1 and the recombinant human DNase Pulmozyme)®. This study aims at validating a new method to remove DNA from donated dermis via the use of a single enzyme, Benzonase, known for its effectiveness of DNA digestion. Skin samples were decellularised by removing the epidermis, lysing of dermal cells, removal of cellular fragments by a detergent wash and removal of nucleic acids by a nuclease incubation with either Benzonase or Pulmozyme + RNase T1. DNA quantification with PicoGreen, as well as histology on wax-embedded biopsies, stained with DAPI and haemotoxylin and eosin, were performed. In vitro toxicity test on human osteosarcoma immortalised cells and skin fibroblasts, and biomechanical (tensile) testing, were also performed. The effectiveness of DNA digestion with the new methodology was comparable to previous procedure. Mean DNA removal percentage following decellularisation with Pulmozyme + RNase was 99.9% (3.83 ng/mg). Mean DNA removal percentage with Benzonase was 99.8% (9.97 ng/mg). Histology staining showed complete decellularisation following either method. Benzonase was proven to be non-toxic to both cell lines used, and a one-way Anova test showed no significant difference in neither stress nor strain between acellular dermal matrix decellularised with either Benzonase or Pulmozyme + RNase T1. Benzonase was able to effectively decellularise dermis after prior removal of epidermis. It performed just as well as the combination of Pulmozyme + RNase T1, but represents significant advantages in terms of cost effectiveness, procurement and storage; Benzonase has been successfully used in the decellularisation of other tissues, thus would be better for Tissue Banking use. Switching to this combined DNase/RNase can have far-reaching consequences in the production of acellular human dermal matrix by NHSBT and in the treatment of patients requiring it.

This study aimed to investigate whether extracellular vesicles (EVs) derived from adipose-derived mesenchymal stem cells (ASCs) promote skin wound healing by delivering basic fibroblast growth factor (bFGF) to enhance vascular endothelial growth factor (VEGF) expression. ASCs were isolated and transfected with either a bFGF knockdown lentivirus (Lv-sh-bFGF) or a control lentivirus (Lv-sh-NC). EVs were extracted from ASCs cultures and characterized by transmission electron microscopy, nanoparticle tracking analysis, and Western blotting for surface markers. EVs were extracted from the conditioned mediums of ASCs and subjected to different treatments. These EVs or control treatments were injected at the wound edges. Wound healing was assessed using histological techniques, including H&E and Masson's trichrome staining to evaluate tissue regeneration, collagen organization, and immunohistochemistry for CD31 to quantify microvessel density. Protein expression of bFGF and VEGF was measured by Western blotting. ASC-derived EVs significantly promoted angiogenesis and improved skin wound healing. EVs encapsulating bFGF enhanced VEGF expression in the wound tissue, while knockdown of bFGF reduced both bFGF and VEGF expression, leading to delayed wound healing. Further knockdown of VEGF partially reversed the pro-angiogenic and wound-healing effects of bFGF-encapsulated EVs. This study demonstrates that ASC-derived EVs promoted skin wound repair by enhancing angiogenesis and accelerating tissue regeneration through the bFGF/VEGF axis. These findings highlight the therapeutic potential of ASCs-derived EVs in improving skin wound healing.

It is common practice that allograft tissues for knee multiligament reconstruction, meniscus transplantation, cartilage replacement and other advanced procedures are made available through commercial banks. The aim was to present the 10-year experience with a local, non-commercial tissue bank, established in 2014. The allograft bank was connected to an existing organ donor program. Following organ procurement, the musculoskeletal tissue is removed and stored immediately, fresh frozen to − 80 degrees Celsius (except hyaline cartilage, which is stored at 5 degrees Celsius). The donor is tested for contagious disease and the grafts for bacteria. When all results are negative, the grafts are released. When thawed before use a swap is cultured. Consecutive, prospectively collected data were analyzed. There were 31 donations, resulting in 1160 grafts. Only 40 grafts (3.4%) had a positive bacteria culture and were discarded. 552 recipients have been treated by use of these allografts. All grafts had negative bacterial cultures in swaps obtained before thawing, and there were no recorded transplantation related complications. The expenses for local grafts were 10–15% of the costs for grafts obtained from foreign banks. Through the local donation program, it was possible to establish a tissue bank with controlled quality grafts at minimal costs, minimizing the need for transportation of frozen grafts retrieved in other countries. Centers for specialized orthopedic surgery using allograft tissue can be self-providing and reduce costs by retrieving and handling allograft tissues locally.

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Bowman's layer is an acellular corneal structure, which is considered to be a specially modified anterior stroma. It is presumed, that it forms as a result of ongoing epithelial-stromal interactions and no clear physiological purpose has been proven. Despite this fact, Bowman's layer has found its place in corneal transplantation. It has been performed for over adecade, mainly in treatment of advanced keratoconus with multiple modifications. Transplantation of Bowman's layer can be expected to become a widely used surgical procedure in the treatment of many corneal pathologies involving fragmentation and destruction of Bowman's layer. This article aims to summarize information available on its structure, possible function, and transplantation. A thorough literature search was performed in the PubMed database and Google Scholar using keywords: Bowman's layer, structure, function, preparation and corneal transplantation. All the relevant sources were used, which represent 77 peer-reviewed articles with information corcerning the topic of this article.