Journal of immunology and regenerative medicine最新文献

The final United Kingdom Regenerative Medicine Platform (UKRMP) conference held in Edinburgh's iconic McEwan Hall between 8th and November 10, 2023 saw a gathering of nearly 200 international delegates presenting exceptional science and celebrating a decade of this initiative. The UKRMP had the core mission to break down the major barriers to clinical translation of regenerative medicine products. UKRMP2 was established as three hubs that worked closely with industry and regulators: 1) Pluripotent Stem Cells and Engineered Cells, 2) Engineered Cell Environments, and 3) Smart Materials. In this meeting report, we outline the original aims of UKRMP, examine how it achieved critical mass, summarise the major developments that the UKRMP hubs delivered, and examine some unresolved challenges that still lie ahead in the field of regenerative medicine.

Objectives

The continuing shortage of organs from deceased human donors prevents many patients with end-stage organ failure from receiving an organ transplant. Xenotransplantation, specifically the transplantation of organs from gene-edited pigs, might resolve the problem of organ supply.

Key findings

When transplanted into nonhuman primates, wild-type (i.e., genetically-unmodified) pig organs are rejected within minutes or hours by antibody-dependent complement-mediated injury and the effect of innate immune cells. With regard to the transplantation of pig kidneys and hearts (but not yet of livers or lungs), this response has largely been overcome by judicious gene-editing of the organ-source pig. Pigs with 10 or more gene edits are now available. However, the adaptive immune response to the graft still needs to be suppressed. Conventional immunosuppressive therapy, e.g., tacrolimus-based, is largely unsuccessful, whereas agents that block the CD40/CD154 T cell co-stimulation pathway are more effective.

Conclusions

The combination of gene-edited pig organs and co-stimulation blockade has extended life-supporting pig kidney survival to months or years and pig heart survival to a maximum of 9 months. However, consistent survival cannot yet be guaranteed and this needs to be achieved before formal clinical trials are initiated. Selection of patients for the initial clinical trials will be important. Patients aged 55–65 years with no or minimal comorbidities who are unlikely ever to receive a deceased human donor kidney would seem suitable candidates. Infants with life-threatening complex congenital heart disease who could be successfully bridged by a pig heart until an allograft became available would appear suitable candidates for pig heart transplantation.

Immunotherapy is a powerful technique where immune cells are modified to improve cytotoxicity against cancerous cells to treat cancers that do not respond to surgery, chemotherapy, or radiotherapy. Expressing chimeric antigen receptor (CAR) in immune cells, typically T lymphocytes, is a practical modification that drives an immune response against cancerous tissue. CAR-T efficacy is suboptimal in solid tumors due to the tumor microenvironment (TME) that limits T lymphocyte cytotoxicity. In this study, we demonstrate that neutrophils differentiated from human pluripotent stem cells modified with AAVS1-inserted CAR constructs showed a robust cytotoxic effect against prostate-specific membrane antigen (PSMA) expressing LNCaP cells as a model for prostate cancer in vitro. Our results suggest that engineered CARs can significantly enhance the neutrophil anti-tumor effect, providing a new avenue in treating prostate cancers.

The gastroesophageal junction (GEJ) plays a critical role in preventing reflux of stomach contents into the esophagus and airways, but currently there are no options for replacement. Surgical resection of the GEJ or lower esophagus requires reanastomosis through a gastric conduit or intestinal interposition, but these surgeries are associated with significant morbidity and mortality related to loss of the one-way valve function. Despite significant progress made in tissue-engineering for the body of the esophagus, little has been done for the stomach and no attempts have been made to reconstruct a GEJ. A detailed understanding of the GEJ anatomy and physiology complemented by knowledge of approaches used in tissue engineering of the esophagus and stomach is foundational to future attempts to address this gap in the field. These topics, as well as anticipated obstacles, are addressed in this review.

Introduction

End-stage or chronic esophageal disease may eventually lead to surgical intervention and could potentially result in an esophagectomy, followed by a gastric pull-up or colon interposition procedure. Biostage's Cellspan™ Esophageal Implant (CEI) is designed to repair and replace full-circumferential esophageal surgical resections (≤6 cm) using autologous adipose derived mesenchymal stromal cells (Ad-MSCs) seeded on a retrievable polyurethane scaffold. The use of a segmental implant has the advantage of preserving the native non-diseased esophageal tissue as well as the stomach or intestinal tissue following esophagectomy. The mechanism of action, the fate of the Ad-MSC component (biodistribution) and the process of early tissue regrowth/wound repair following implantation remains to be elucidated.

Methods

CEIs seeded with Ad-MSCs transduced with green fluorescent protein (GFP) were implanted into a pig model of esophageal segmental resection. A 5 cm full-circumferential esophageal resection was performed followed by CEI implantation using an end-to-end anastomoses to bridge the gap between the 2 native esophageal ends. Cell fate and tissue development were assessed at 14 (N = 3), 21 (N = 3), and 28 days (N = 3), post-CEI implantation.

Results

All animals in all groups exhibited a contiguous biologic esophageal conduit with a denuded patent lumen at necropsy. Epithelial cell proliferation/regrowth was evident from both anastomotic margins toward the implant center. Morphometric analysis indicated an increase in epithelial regrowth and a concomitant reduction in denuded tissue from day 14 to day 28. Histological evaluation revealed fibrovascular tissue and neovascularization on the adventitial side, with no discernible differences in tissue organization between 14 and 28 day implants. The majority of GFP + cells were on the abluminal esophageal surface and localized around vascular structures. No GFP + cells were detected in lymph nodes or on retrieved scaffolds.

Conclusion

These findings support luminal continuity by day 14 post-implantation with Ad-MSC derived pericytes contributing to the neo-fibrovascular tissue. Morphometric analysis of the lumenal surface indicates that the process of lumenal re-epithelialization results from epithelial cell proliferation from the implant margins towards the center of the implant.

Calcium phosphates with submicron surface features have demonstrated superior performance to conventional calcium phosphates and equivalence to autologous bone in pre-clinical bone healing models. This is related to their ability to form bone in soft tissues, without the addition of cells and growth factors. It is hypothesized that a specific innate immune response to submicron topography contributes to the enhanced bone healing by these materials. Upregulation of pro-healing, anti-inflammatory ‘M2’ macrophages versus pro-inflammatory ‘M1’ macrophages on submicron-structured calcium phosphates may be involved. In this in vitro study, the response of primary human macrophages to different calcium phosphate bone graft substitutes was assessed. Primary CD14⁺ monocytes were isolated from human buffy coats and were seeded on two different calcium phosphate materials. The first material had a submicron topography of needle-shaped crystals (BCP_<μm) while the second material had no submicron topography (TCP). Macrophage M1/M2 phenotype characterization by protein and gene expression markers at 24 h and 72 h indicated overall stronger macrophage activation and subtle phenotypic skewing towards the M2 phenotype on BCP_<μm vs TCP. Moreover, macrophages exhibited an elongated morphology on BCP_<μm, which is associated with the M2 phenotype, while macrophages on TCP primarily exhibited a spherical morphology. Conditioned medium of macrophages cultured on BCP_<μm resulted in enhanced in vitro angiogenic tube formation and osteogenic differentiation of mesenchymal stromal cells, compared to conditioned medium from macrophages on TCP. Altogether, these findings suggest a potential role of M2 macrophage upregulation in the bone-induction mechanism of calcium phosphates with submicron surface topography.

Introduction

We reported the short-term outcomes of a regenerative medical treatment to prevent esophageal stricture after endoscopic submucosal dissection (ESD) using cultured tis oral mucosal epithelial cell sheets. This study investigated the long-term outcomes of this treatment.

Methods

Epithelial cells, isolated from the patient's own oral mucosal tissue, were cultured for 16 days using temperature-responsive culture dishes. Then, the autologous cell sheets were endoscopically transplanted onto the bed of the esophageal ulcer after endoscopic mucosal resection (EMR) and ESD. Results of 10 patients who underwent endoscopic transplantation of oral mucosal epithelial cell sheets from April 2008 through February 2022 were recorded. We analyzed the outcome, the cause, and the endoscopic findings.

Results

The median period of observation was 3761 days. No stricture was detected in any of the patients long-term. Two patients died because of pancreatic cancer and brainstem hemorrhage. One patient underwent chemo-radiotherapy for further treatment. The patients underwent surgery due to metastasis to the lymph nodes. Only the lymph nodes were dissected, and the esophagus remained intact. From the endoscopic findings: Melanosis was found at the transplanted site in a patient. Strong iodine staining was shown at the transplanted site in a patient. Transplantation of cultured oral mucosal epithelial cell sheets to prevent esophageal stricture has been proven to be a safe treatment. All patients showed no controlled esophageal stricture in the long term.