Regulatory T cell niche in the bone marrow, a new player in Haematopoietic stem cell transplantation.

Challenges in haematopoietic stem cell transplantation such as low bone marrow (BM) engraftment, graft versus host disease (GvHD) and the need for long-term immunosuppression could be addressed using T regulatory cells (Tregs) resident in the tissue of interest, in this case, BM Tregs. Controlling the adverse immune response in haematopoietic stem cell transplantation (HSCT) and minimising the associated risks such as infection and secondary cancers due to long-term immunosuppression is a crucial aspect of clinical practice in this field. While systemic immunosuppressive therapy could achieve reasonable GvHD control in most patients, related side effects remain the main limiting factor. Developing more targeted immunosuppressive strategies is an unmet clinical need and is the focus of several ongoing research projects. Tregs are a non-redundant sub-population of CD4+ T cells essential for controlling the immune homeostasis. Tregs are known to be reduced in number and function in autoimmune conditions. There is considerable interest in these cells as cell therapy products since they can be expanded in vitro and infused into patients. These trials have found Treg therapy to be safe, well-tolerated, and with some early signs of efficacy. However, Tregs are a heterogeneous subpopulation of T cells, and several novel subpopulations have been identified in recent years beyond the conventional thymic (tTregs) and peripheral (pTregs). There is increasing evidence for the presence of resident and tissue-specific Tregs. Bone marrow (BM) Tregs are one example of tissue-resident Tregs. BM Tregs are enriched within the marrow, serving a dual function of immunosuppression and maintenance of haematopoietic stem cells (HSCs). HSCs maintenance is achieved through direct suppression of HSCs differentiation, maintaining a proliferating pool of HSCs, and promoting the development of functional stromal cells that support HSCs. In this review, we will touch upon the biology of Tregs, focusing on their development and heterogeneity. We will focus on the BM Tregs from their biology to their therapeutic potential, focusing on their use in HSCT.

Mitral valve surgery via repeat median sternotomy versus right mini-thoracotomy: A systematic review and meta-analysis of clinical outcomes.

BACKGROUND: Redo mitral valve surgeries have high mortality and morbidity and can be physically demanding for patients. Median sternotomy remains the gold standard for most cardiac surgeries. To tackle certain risks with a re-sternotomy, alternative procedures such as the right anterolateral minithoracotomy have been explored. This review aims to compare the clinical outcomes of re-sternotomy (MS) versus right mini thoracotomy (MT) in mitral valve surgery. METHODS: A systematic, electronic search was performed according to Preferred Reporting items for Systematic Reviews and Meta-analysis guidelines to identify relevant articles that compared outcomes of the MS versus MT procedures in patients who have had cardiac surgery via a MS approach. RESULTS: Twelve studies were identified, enrolling 4514 patients. Length of hospital stay(MD = -3.71, 95% confidence interval [CI] [-4.92, -2.49]), 30-day mortality(odds ratio [OR] = 0.59, 95% CI [0.39, 0.90]), and new-onset renal failure(OR = 0.38, 95% CI [0.22, 0.65]) were statistically significant in favor of the MT approach. Infection rates(OR = 0.56, 95% CI[0.25, 1.21]) and length of intensive care unit (ICU) stay (MD = -0.55, 95% CI[-1.16, 0.06]) was lower in the MT group; however, the difference was not significant. No significant differences were observed in the CPB time(MD = -2.33, 95% CI [-8.15, 3.50]), aortic cross-clamp time MD = -1.67, 95% CI[-17.07, 13.76]), and rates of stroke(OR = 1.03, 95% CI[0.55, 1.92]). CONCLUSION: Right MT is a safe alternative to the traditional re-sternotomy for patients who have had previous cardiac surgery. The approach offers a reduced length of hospital stay, ICU stay, and a lower risk of new-onset renal failure requiring dialysis. This review calls for robust trials in the field to further strengthen the evidence.