Reduced endothelial activation upon human blood perfusion of pig kidney xenografts lacking MHC class I and three xenoantigens

Genetically tailored pigs to eliminate human immune rejection of xenografts is one promising solution to the global donor organ shortage. The development of xenograft transplantation has however been hampered by incomplete understanding of its immune rejection and the inability to test this in a human transplantation setting. Here we use an ex vivo organ perfusion system with human whole blood to assess the initial immune activation within the xenograft endothelium at single cell transcriptome level. Renal injury, complement deposition, coagulation and lymphocyte influx are all strongly reduced in genetically modified pig kidneys with porcine MHC class I and three xenoantigens (GGTA1, CMAH, B4GALNT2) eliminated (4KO) compared to wildtype (WT) pig kidneys after 6-hours human blood perfusion. Single cell RNA sequencing of endothelial cells (EC) from 4KO and WT pig kidneys respectively reveal that there is a compartment (cortex, glomeruli and medulla) specific endothelial activation, with cortical and glomeruli endothelial cells being more affected. Differential gene expression analysis shows a downregulation of endothelial transcriptome activation response to human blood perfusion in the 4KO ECs. Pathway enrichment analysis further identify the NF-kB pathway as strongly activated in human blood perfused WT ECs but diminished in the 4KO. In conclusion, the 4KO pig model has strongly reduced endothelial immune activation response when perfused with human whole blood, that goes beyond prevention of humoral rejection. Our data support further development of the 4KO for use in clinical transplantation.

Modified Tectonic Corneoscleral Graft For Management of Devastating Corneoscleral Infections

Purpose To analyze the clinical results and the efficacy of modified tectonic corneoscleral graft (TCG) in patients with devastating corneoscleral infections.Methods Twenty-five eyes from 25 patients who underwent modified TCG were enrolled. The recurrence, best-corrected visual acuity (BCVA), ocular surface stability, postoperative complications and graft survival condition were recorded.Results Among 25 patients, 19 cases were fungal infection and 6 cases were bacterial. The rate of recurrence was 8% with Pythium Insidiosum as a corresponding pathogen. The rate of monocular blindness declined from 100% to 57%. Changes in BCVA from preoperative to postoperative values were significant ( Z=4.22, P＜0.001). The survival of ocular surface stability was 73.6% and 43.9% at 1 and 3 years after surgery, respectively. Within the mean follow-up period of 17.5 ± 8.9 months, 21eyes (84.0%) had a stable ocular surface. The incidence rate of immune rejection was 36%. Corneal epithelial defects occurred in 7 patients and choroidal detachment occurred in 3 patients. No elevation of intraocular pressure was detected.Conclusions The modified TCG is effective in eradicating infection, salvaging the eyeball and saving some useful vision for devastating corneoscleral infections. Regular application of tacrolimus, timely addition of glucocorticoid and good compliance may decrease the postoperative course challenging.

Regeneration and Diagnosis of Kidney Disease Using Exosomes

: A growing global prevalence of acute kidney injury (AKI) and chronic kidney disease (CKD), high costs of kidney transplantation, a shortage of kidney donors, and low survival rate after dialysis have popularized mesenchymal stem cell (MSC) therapy via transplantation. However, the risks of tumorigenesis, immune rejection, pathogen transmission, loss of differentiation, and morphological changes after long-term culture have prompted researchers to develop a safer and more effective therapy method. Therefore, cell-free approaches have been developed to reduce the risks associated with stem cell-based therapies. In cell-free therapy of AKI and CKD, MSC-derived extracellular vesicles, with nanometer sizes, are used, called exosomes. Exosomes have a lipid bilayer membrane with various genes, microRNAs, and proteins for kidney repair. As known, MSC-derived exosomes have improved the kidney regeneration process for various reasons, such as increased safety and reduced inflammation, immune rejection, and tumorigenesis. With the advancement of exosome isolation techniques, the possibility of using biologically active molecules for renal injury prediction and diagnosis has emerged. The use of urinary exosomes in AKI and CKD diagnosis is based on changes in the expression of specific molecule cargos of exosomes. This review article summarizes the diagnosis and therapeutic applications of exosomes in AKI and CKD.

The Latest Developments in Immunomodulation of Mesenchymal Stem Cells in the Treatment of Intrauterine Adhesions, Both Allogeneic and Autologous

Intrauterine adhesion (IUA) is an endometrial fibrosis disease caused by repeated operations of the uterus and is a common cause of female infertility. In recent years, treatment using mesenchymal stem cells (MSCs) has been proposed by many researchers and is now widely used in clinics because of the low immunogenicity of MSCs. It is believed that allogeneic MSCs can be used to treat IUA because MSCs express only low levels of MHC class I molecules and no MHC class II or co-stimulatory molecules. However, many scholars still believe that the use of allogeneic MSCs to treat IUA may lead to immune rejection. Compared with allogeneic MSCs, autologous MSCs are safer, more ethical, and can better adapt to the body. Here, we review recently published articles on the immunomodulation of allogeneic and autologous MSCs in IUA therapy, with the aim of proving that the use of autologous MSCs can reduce the possibility of immune rejection in the treatment of IUAs.

Using wide biological pores to cap and contain the COVID-19 spike protein

Geometric analysis shows that the spike (S) protein in the COVID-19 virus (SARS-Cov-2) can fully or partially enter into the channel of a wide biological pore like perforin (PFN) or streptolysin (SLO) when the latter is anchored in a bilayer lipid membrane. The PFN channel is a β barrel formed from multiple monomers, for example a ~14 nm diameter channel is formed from 22 monomers. Coincidentally the wide canopy of S (which has three identical chains) has an enclosing diameter of ~14 nm. While inside the channel peripheral residues in the canopy may bind with residues on the pore side of the barrel. If there are no adverse cross-reactions this would effectively prevent S from interacting with a target cell. Calculations with data obtained from PDB and other sources show that there are ~12 peripheral residue triples in S within a circle of diameter ~14 nm that can potentially bind with 22 exposed residues in each barrel monomer. The revised Miyazawa-Jernighan matrix is used to calculate the binding energy of canopy-PFN barrel residue pairs. The results show a large number of binding pairs over distances of up to 38 Å into the pore. This geometric view of capture and containment points to the possibility of using biological pores to neutralize SARS-Cov-2 in its many variant forms. Some necessary conditions that must be satisfied for such neutralization to occur are noted. A wide pore (such as PFN or SLO) can also be used in an electrolytic cell to detect the presence of SARS-Cov-2, which would cause a large-sized blockade of the base current (the ionic current in a fully open pore). It can further be used to quantify the virus level in the sample. Solid-state pores, which have several advantages over biological ones, can be used instead; immune rejection is not an issue and there is no need for the spike or the virus to bind to the pore.

Cell Transplantation Therapies to Reverse Type 1 Diabetes: A review

Stem cell technology is demonstrating promising advancements in cure of diseases due its differentiation ability. Type 1 diabetes is mainly caused by autoimmune ? cells destruction. In this review, we focus on treatment procedures of Type 1 Diabetes (T1D) with numerous stem cells (SCs) i.e hPSCs, MSCs, hESCs, BMSCs, AFSCs, HSCs and islet cells (that are not stem cells but they are approved worldwide and are being successfully used to permanently reverse T1D). A brief overview of this disease along with the advancements in treatment of T1D with stem cells is discussed. Biomaterial encapsulation to avoid immune rejection and improved immunomodulation and immune tolerance via drugs /bioengineering techniques makes the outcomes of SC therapies more efficient and productive, hence, proving to be another future milestone of completely reversing type 1 diabetes especially in those patients who got clinically diagnosed at an early stage and then received prompt treatment of either restoration of already available ? cells functionality or transplantation of purified and functional SCs differentiated insulin producing cells to normalize the glycemic control and homeostasis. Keywords: Type 1 Diabetes, ?-cells, Stem cells, Biomaterial

Placental Immune Tolerance and Organ Transplantation: Underlying Interconnections and Clinical Implications

The immune system recognizes and attacks non-self antigens, making up the cornerstone of immunity activity against infection. However, during organ transplantation, the immune system also attacks transplanted organs and leads to immune rejection and transplantation failure. Interestingly, although the embryo and placenta are semi-allografts, like transplanted organs, they can induce maternal tolerance and be free of a vigorous immune response. Also, embryo or placenta-related antibodies might adversely affect subsequent organ transplantation despite the immune tolerance during pregnancy. Therefore, the balance between the immune tolerance in maternal-fetal interface and normal infection defense provides a possible desensitization and tolerance strategy to improve transplantation outcomes. A few studies on mechanisms and clinical applications have been performed to explore the relationship between maternal-fetal immune tolerance and organ transplantation. However, up to now, the mechanisms underlying maternal-fetal immune tolerance remain vague. In this review, we provide an overview on the current understanding of immune tolerance mechanisms underlying the maternal-fetal interface, summarize the interconnection between immune tolerance and organ transplantation, and describe the adverse effect of pregnancy alloimmunization on organ transplantation.