Timing of Mesenchymal Stromal Cell Therapy Defines its Immunosuppressive Effects in a Rat Lung Transplantation Model.

Cell therapy using mesenchymal stromal cells (MSCs) is being studied for its immunosuppressive effects. In organ transplantation, the amount of MSCs that accumulate in transplanted organs and other organs may differ depending on administration timing, which may impact their immunosuppressive effects. In vitro, adipose-derived mesenchymal stem cells (ADMSCs) suppress lymphocyte activation under cell-to-cell contact conditions. However, in vivo, it is controversial whether ADMSCs are more effective in accumulating in transplanted organs or in secondary lymphoid organs. Herein, we aimed to investigate whether the timing of ADMSC administration affects its immunosuppression ability in a rat lung transplantation model. In the transplantation study, rats were intramuscularly administered half the usual dose of tacrolimus (0.5 mg/kg) every 24 h after lung transplantation. ADMSCs (1 × 106) were administered via the jugular vein before (PreTx) or after (PostTx) transplantation. Cell tracking using quantum dots was performed. ADMSCs accumulated predominantly in the lung and liver; fewer ADMSCs were distributed in the grafted lung in the PreTx group than in the PostTx group. The rejection rate was remarkably low in the ADMSC-administered groups, particularly in the PostTx group. Serum tumor necrosis factor-α (TNF-α), interferon-γ, and interleukin (IL)-6 levels showed a greater tendency to decrease in the PreTx group than in the PostTx group. The proportion of regulatory T cells in the grafted lung 10 days after transplantation was higher in the PostTx group than in the PreTx group. PostTx administration suppresses rejection better than PreTx administration, possibly due to regulatory T cell induction by ADMSCs accumulated in the transplanted lungs, suggesting a mechanism different from that in heart or kidney transplantation that PreTx administration is more effective than PostTx administration. These results could help establish cell therapy using MSCs in lung transplantation.

Adipose-Derived Mesenchymal Stem Cells Attenuate Immune Reactions Against Pig Decellularized Bronchi Engrafted into Rat Tracheal Defects.

Decellularized scaffolds are promising biomaterials for tissue and organ reconstruction; however, strategies to effectively suppress the host immune responses toward these implants, particularly those without chemical crosslinking, remain warranted. Administration of mesenchymal stem cells is effective against immune-mediated inflammatory disorders. Herein, we investigated the effect of isogeneic abdominal adipose-derived mesenchymal stem/stromal cells (ADMSCs) on xenogeneic biomaterial-induced immunoreactions. Peripheral bronchi from pigs, decellularized using a detergent enzymatic method, were engrafted onto tracheal defects of Brown Norway (BN) rats. BN rats were implanted with native pig bronchi (Xenograft group), decellularized pig bronchi (Decellularized Xenograft), or Decellularized Xenograft and ADMSCs (Decellularized Xenograft+ADMSC group). In the latter group, ADMSCs were injected intravenously immediately post implantation. Harvested graft implants were assessed histologically and immunohistochemically. We found that acute rejections were milder in the Decellularized Xenograft and Decellularized Xenograft+ADMSC groups than in the Xenograft group. Mild inflammatory cell infiltration and reduced collagen deposition were observed in the Decellularized Xenograft+ADMSC group. Additionally, ADMSC administration decreased CD8+ lymphocyte counts but increased CD163+ cell counts. In the Decellularized Xenograft+ADMSC group, serum levels of vascular endothelial growth factor and IL-10 were elevated and tissue deposition of IgM and IgG was low. The significant immunosuppressive effects of ADMSCs illustrate their potential use as immunosuppressive agents for xenogeneic biomaterial-based implants.

Donor and Recipient Adipose-Derived Mesenchymal Stem Cell Therapy for Rat Lung Transplantation.

BACKGROUND: Mesenchymal stem cells (MSCs) are beginning to be proven as immunosuppressant in the field of organ transplantation. However, the effects of MSC origin (donor or recipient) on immunosuppression are not clear. Hence, we investigated the effects of recipient and donor adipose-derived MSCs (ADMSCs) on immunosuppression in a rat lung transplantation model. METHODS: Subjects were divided into no treatment, tacrolimus administration, recipient ADMSC administration, donor ADMSC administration, and mixed donor and recipient ADMSC administration groups. ADMSC-administered groups were also treated with tacrolimus. Histologic study, immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay, and polymerase chain reaction were used for various analyses. RESULTS: Fluorescently labeled ADMSCs were predominant in the grafted donor lung, but not in the recipient lung, on day 5. On day 7, the pathologic rejection grades of the grafted donor lung were significantly lower in the ADMSC-administered groups (P < .05) and did not differ among these groups. Although serum hepatocyte growth factor and vascular endothelial growth factor levels did not differ among the groups, interleukin 10 level was slightly higher in the ADMSC-administered groups. The numbers of infiltrating regulatory T cells in the grafted lung were significantly higher in the ADMSC-administered groups (P < .05) but did not differ with cell origin. Transcriptional analysis suggested interleukin 6 suppression to be the main overlapping immunosuppressive mechanism, regardless of origin. Therefore, a donor or recipient origin may not influence the immunosuppressive efficacy of ADMSCs in our rat lung transplantation model. CONCLUSIONS: Collectively, the results indicate that allogenic ADMSCs, regardless of their origin, may exert similar immunosuppressive effects in clinical organ transplantation.

Successful pulmonary artery stenting for occlusion at a constructed pericardial conduit after right upper double sleeve lobectomy.

The patient was a 53-year-old man. His chief complaint was a cough and dyspnea on exertion. Computed tomography (CT) showed a 3-cm-diameter tumor in the right upper lobe with invasion from hilar lymph nodes to the superior vena cava, right main bronchus, and pulmonary artery. After being diagnosed with non-small cell lung cancer, the patient underwent preoperative induction radiochemotherapy. At surgery, right upper double sleeve lobe lobectomy was performed. The right main pulmonary artery was reconstructed using a pericardial conduit. CT 1 week after surgery showed impaired blood flow in the right pulmonary artery. A metal vascular stent was inserted into the narrow part of the constructed pulmonary artery in the hybrid operating room because thrombectomy was unsuccessful. After surgery, contrast CT showed that blood flow was maintained. The patient is currently well without any recurrence 3 years after surgery.

Anticancer agent α-sulfoquinovosyl-acylpropanediol enhances the radiosensitivity of human malignant mesothelioma in nude mouse models.

Malignant pleural mesothelioma (MPM) is a highly malignant disease that develops after asbestos exposure. Although the number of MPM cases is predicted to increase, no effective standard therapies have been established. The novel radiosensitizer α-sulfoquinovosyl-acylpropanediol (SQAP) enhances the effects of γ-radiation in human lung and prostate cancer cell lines and in animal models. In this study, we explored the radiosensitizing effect of SQAP and its mechanisms in MPM. The human MPM cell lines MSTO-211H and MESO-4 were implanted subcutaneously into the backs and thoracic cavities of immunodeficient KSN/Slc mice, then 2 mg/kg SQAP was intravenously administered with or without irradiation with a total body dose of 8 Gy. In both the orthotopic and ectopic xenograft murine models, the combination of irradiation plus SQAP delayed the implanted human MSTO-211H tumor growth. The analysis of the changes in the relative tumor volume of the MSTO-211H indicated a statistically significant difference after 8 Gy total body combined with 2 mg/kg SQAP, compared to both the untreated control (P = 0.0127) and the radiation treatment alone (P = 0.0171). After the treatment in each case, immunostaining of the harvested tumors revealed decreased cell proliferation, increased apoptosis and normalization of tumor blood vessels in the SQAP- and irradiation-treated group. Furthermore, hypoxia-inducible factor (HIF) 1 mRNA and protein expression were decreased, indicating reoxygenation in this group. In conclusion, SQAP improved hypoxic conditions in tumor tissue and may elicit a radiosensitizing effect in malignant mesothelioma models.

Increased In Vitro Intercellular Barrier Function of Lung Epithelial Cells Using Adipose-Derived Mesenchymal Stem/Stromal Cells.

With the emergence of coronavirus disease-2019, researchers have gained interest in the therapeutic efficacy of mesenchymal stem/stromal cells (MSCs) in acute respiratory distress syndrome; however, the mechanisms of the therapeutic effects of MSCs are unclear. We have previously reported that adipose-derived MSCs (AD-MSCs) strengthen the barrier function of the pulmonary vessels in scaffold-based bioengineered rat lungs. In this study, we evaluated whether AD-MSCs could enhance the intercellular barrier function of lung epithelial cells in vitro using a transwell coculture system. Transepithelial electrical resistance (TEER) measurements revealed that the peak TEER value was significantly higher in the AD-MSC coculture group than in the AD-MSC non-coculture group. Similarly, the permeability coefficient was significantly decreased in the AD-MSC coculture group compared to that in the AD-MSC non-coculture group. Immunostaining of insert membranes showed that zonula occuldens-1 expression was significantly high at cell junctions in the AD-MSC coculture group. Moreover, cell junction-related gene profiling showed that the expression of some claudin genes, including claudin-4, was upregulated in the AD-MSC coculture group. Taken together, these results showed that AD-MSCs enhanced the barrier function between lung epithelial cells, suggesting that both direct adhesion and indirect paracrine effects strengthened the barrier function of lung alveolar epithelium in vitro.

Expression of human CD47 in pig glomeruli prevents proteinuria and prolongs graft survival following pig-to-baboon xenotransplantation.

BACKGROUND: Nephrotic syndrome is a common complication of pig-to-baboon kidney xenotransplantation (KXTx) that adversely affects outcomes. We have reported that upregulation of CD80 and down-regulation of SMPDL-3b in glomeruli have an important role in the development of proteinuria following pig-to-baboon KXTx. Recently we found induced expression of human CD47 (hCD47) on endothelial cells and podocytes isolated from hCD47 transgenic (Tg) swine markedly reduced phagocytosis by baboon and human macrophages. These observations led us to hypothesize that transplanting hCD47 Tg porcine kidneys could overcome the incompatibility of the porcine CD47-baboon SIRPα interspecies ligand-receptor interaction and prevent the development of proteinuria following KXTx. METHODS: Ten baboons received pig kidneys with vascularized thymic grafts (n = 8) or intra-bone bone marrow transplants (n = 2). Baboons were divided into three groups (A, B, and C) based on the transgenic expression of hCD47 in GalT-KO pigs. Baboons in Group A received kidney grafts with expression of hCD47 restricted to glomerular cells (n = 2). Baboons in Group B received kidney grafts with high expression of hCD47 on both glomerular and tubular cells of the kidneys (n = 4). Baboons in Group C received kidney grafts with low/no glomerular expression of hCD47, and high expression of hCD47 on renal tubular cells (n = 4). RESULTS: Consistent with this hypothesis, GalT-KO/hCD47 kidney grafts with high expression of hCD47 on glomerular cells developed minimal proteinuria. However, high hCD47 expression in all renal cells including renal tubular cells induced an apparent destructive inflammatory response associated with upregulated thrombospondin-1. This response could be avoided by a short course of weekly anti-IL6R antibody administration, resulting in prolonged survival without proteinuria (mean 170.5 days from 47.8 days). CONCLUSION: Data showed that transgenic expression of hCD47 on glomerular cells in the GalT-KO donor kidneys can prevent xenograft nephropathy, a significant barrier for therapeutic applications of xenotransplantation. The ability to prevent nephrotic syndrome following KXTx overcomes a critical barrier for future clinical applications of KXTx.

Safety, efficacy, and analysis of key parameters after prophylactic administration of a sustained-release formulation of azithromycin in lung cancer surgery.

BACKGROUND: The current use of prophylactic antibiotics for lung cancer surgery requires modification in aging individuals with impaired lung function. A sustained-release formulation of azithromycin (AZM-SR) could help resolve some of these challenges with its sustained antibacterial and anti-inflammatory effects. The aim of this study was to examine the safety and efficacy of AZM-SR in lung cancer surgery as well as its anti-inflammatory effect. METHODS: Fifty patients were included in the study, and AZM-SR was administered 1 day prior to the surgery. The clinical course, including postoperative complications, was monitored, and the concentration of AZM, bacterial culture, and inflammatory cytokine levels of resected lung specimens were evaluated. RESULTS: No side effects related to AZM-SR were observed. Five cases of postoperative pneumonia (10%) were observed; technical issues were involved in 3 cases. All patients recovered well. Four cases showed positive bacterial culture upon lung tissue examination; however, this was not significantly correlated with postoperative complications. A negative correlation was observed between AZM concentration in lung tissue and interleukin-6 (IL-6) expression. CONCLUSIONS: Prophylactic utilization of AZM-SR in lung cancer surgery seems feasible. The anti-inflammatory effect of AZM might contribute additional beneficial effects in the perioperative management of lung cancer surgery.

A randomized phase II study of S-1 monotherapy versus cisplatin with vinorelbine for completely resected stage II/IIIA non-small cell lung cancer: rationale and study protocol design for the LOGIK1702 study.

BACKGROUND: The current standard postoperative treatment for stage II-IIIA non-small cell lung cancer (NSCLC) is a regimen of platinum doublet adjuvant chemotherapy. These regimens, which are the same as for solid NSCLC tumors, often cause severe adverse reactions in the treated patients. Therefore, an effective treatment regimen with fewer side effects is needed. METHODS/DESIGN: The purpose of this study is to evaluate the effectiveness and safety of S-1 monotherapy (80 mg/m2 orally administrated twice daily, at day 1-14, 16 cycles) and cisplatin with vinorelbine combination therapy (cisplatin 80 mg/m2 at day 1,vinorelbine 25 mg/m2 at day 1, 8, 4 cycles) in patients with II/IIIA stage non-small-cell lung cancer who underwent a total resection. In addition, we will also evaluate the level of treatment side effects by assessing quality of life (QOL), work productivity and activity performance. The primary endpoint is a 2-year relapse free survival (RFS) and the second primary endpoints are 2-year overall survival (OS), rate of treatment completion, safety, work productivity and activity, and quality of adjusted life years (QALY). At the same time, we aim to obtain precise information required to perform future phase 3 randomized controlled trials. The study is designed to estimate the primary endpoint with accuracy determined as the width of its 95% confidence interval to be less than 20%. Recruitment started in May 2017 and is ongoing. DISCUSSION: This study has been conceived to establish a superior regimen for completely resected NSCLC based on efficacy, safety and QOL. TRIAL REGISTRATION: Registry number: UMIN000027435 . Registered May 22, 2017.

Preoperative tracheal resection and reconstruction simulations with patient-specific three-dimensional models.

Three-dimensional (3D) printers are increasingly being used for a variety of applications. In the surgical field, patient-specific organ models are increasingly being used as preoperative simulators for complicated surgeries. In this study, we describe the use of patient-specific 3D models for tracheal resection. We performed preoperative simulations for two patients diagnosed with tracheal ganglioneuroma and adenoid cystic carcinoma; the mimic operations suggested the necessity of a short cuff intubation tube across the surgical field, indicating the recommended amount of dissection around the trachea and bilateral hilum prior to tracheal reconstruction. The postoperative courses were free from any anastomotic or pulmonary complications. We described the availability of preoperative simulations for complicated tracheal resection and reconstruction using patient-specific 3D printed models. Mimic operations using the 3D printed models allowed accurate preparation and confidence in selection of the optimal surgical strategy.

Protection of Pancreatic Islets Using Theranostic Silencing Nanoparticles in a Baboon Model of Islet Transplantation.

The long-term success of pancreatic islet transplantation (Tx) as a cure for type 1 diabetes remains limited. Islet loss after Tx related to apoptosis, inflammation, and other factors continues to limit Tx efficacy. In this project, we demonstrate a novel approach aimed at protecting islets before Tx in nonhuman primates (NHPs) (baboons) by silencing a gene (caspase-3) responsible for induction of apoptosis. This was done using siRNA (siCas-3) conjugated to magnetic nanoparticles (MNs). In addition to serving as carriers for siCas-3, these nanoparticles also act as reporters for MRI, so islets labeled with MN-siCas-3 can be monitored in vivo after Tx. In vitro studies showed the antiapoptotic effect of MN-siCas-3 on islets in culture, resulting in minimal islet loss. For in vivo studies, donor baboon islets were labeled with MN-siCas-3 and infused into recipient diabetic subjects. A dramatic reduction in insulin requirements was observed in animals transplanted with even a marginal number of labeled islets compared with controls. By demonstrating the protective effect of MN-siCas-3 in the challenging NHP model, this study proposes a novel strategy to minimize the number of donor islets required from either cadaveric or living donors.

Enhanced airway stenting using a preoperative, three-dimensionally printed airway model simulation.

Three-dimensionally printed organ models that facilitate preoperative simulations have the potential to improve outcomes of surgical procedures. Here, we report a case involving a 54-year-old man diagnosed with lung cancer of the right upper bronchus that was invading the right main bronchus. A right upper lobectomy with carinoplasty was performed. Although complete excision of the tumor was achieved, exertional dyspnea redeveloped 4 months post-surgery. Chest computed tomography revealed that airway stenosis caused by granulation had deformed the airway. Ablation of the granulation and airway stenting was required to improve the patient's symptoms. Prior to performing airway stenting, a three-dimensionally printed airway model was constructed, and the Y-shaped silicone stent used was modified in accordance with the model. After stenting, both the right and left bronchi were preserved, and the patient's symptoms improved. The three-dimensional printed airway model enhanced the accuracy and safety of the airway stenting procedure performed.

Surgery or stereotactic body radiotherapy for metachronous primary lung cancer? A propensity score matching analysis.

OBJECTIVE: We compared outcomes after surgery or stereotactic body radiotherapy (SBRT) among patients with metachronous primary lung cancer (MPLC). METHODS: Patients with MPLC were treated with either surgery (2008-2018) or SBRT (2010-2018). We used propensity score matching (PSM) to reduce bias from various clinicopathological factors. MPLC was defined by the Martini and Melamed criteria. RESULTS: Of 77 patients, 51 underwent surgery and 26 received SBRT. Most median clinicopathological characteristics did not significantly differ between the surgery and SBRT groups (male sex: 67% vs 65%; age: 73 vs 77 years; time after first surgery: 6.2 vs 4.7 years; lobectomy as first procedure: 82% vs 85%; second tumor size: 11 vs 12 mm; clinical stage I: 96% vs 100%; CEA: 2.9 vs 3.0 ng/ml). However, the surgery group had significantly more ipsilateral second tumors (n = 71, 58%, P = 0.003), better performance status (P = 0.03), and preserved lung function (P = 0.02). Surgery, thus, tended to be selected for patients with good physical function and for the MPLC in the contralateral side. Five-year overall survival did not significantly differ between the surgery and SBRT groups, either before PSM (86.5% vs 65.8%, P = 0.24, log-rank) or after PSM (100% vs 84.4%, P = 0.73). CONCLUSIONS: Surgery and SBRT for MPLC patients are safe and feasible treatments with similar outcomes. However, this finding should be verified by a random controlled trial with a larger study cohort.

Intra-bone bone marrow transplantation from hCD47 transgenic pigs to baboons prolongs chimerism to >60 days and promotes increased porcine lung transplant survival.

BACKGROUND: We have recently demonstrated that human-CD47 (hCD47) expressed on endothelial cells of porcine lung xenografts extended median graft survival from 3.5 days to 8.7 days in baboons. Intra-bone bone marrow transplantation (IBBMTx) in a pig-to-baboon model was previously shown to markedly prolong the duration of macrochimerism up to 21 days from 1 to 4 days by intravenous BMTx. We now examined whether the use of hCD47 transgenic (Tg) BM further prolonged the duration of chimerism following IBBMTx. We then tested if lung xenograft survival was prolonged following IBBMTx. METHODS: Baboons received GalTKO-hCD47/hCD55Tg (n = 5) or -hCD55Tg (n = 1) or -hCD46/HLA-E Tg (n = 1) pig IBBMTx. Macrochimerism, anti-pig T cells and antibody responses were assessed. Animals received lung xenografts from either hCD47+ or hCD47- porcine lungs 1-3 months later. RESULTS: All baboons that received hCD47Tg porcine IBBM maintained durable macrochimerism >30 days, and two maintained chimerism for >8 weeks. Notably, anti-pig antibody levels decreased over time and anti-pig cellular unresponsiveness developed following IBBMTx. Lungs from hCD47Tg IBBMTx matched pigs were transplanted at day 33 or day 49 after IBBMTx. These animals showed extended survival up to 13 and 14 days, while animals that received lungs from hCD47 negative pigs displayed no prolonged survival (1-4 days). CONCLUSION: This is the first report demonstrating durable macrochimerism beyond 8 weeks, as well as evidence for B cell tolerance in large animal xenotransplantation. Using hCD47Tg pigs as both IBBMTx and lung donors prolongs lung xenograft survival. However, additional strategies are required to control the acute loss of lung xenografts.

Transgenic expression of human CD47 reduces phagocytosis of porcine endothelial cells and podocytes by baboon and human macrophages.

BACKGROUND: Our initial studies utilizing a galactosyl-α1-3-galactosyltransferase gene knockout (GalTKO) pig-to-baboon renal transplant model demonstrated that the early development of nephrotic syndrome has been a significant obstacle to the long-term survival of baboon recipients. We have recently documented that sphingomyelin phosphodiesterase-3 (SMPDL3b) and CD80 expressed on podocytes in porcine kidney grafts contribute to this complication. We have hypothesized that one regulator of immune function is CD47 and that incompatibilities in CD47 between pig and baboon could potentially affect macrophage function, increasing the susceptibility of the kidney grafts to immunologically induced injury. METHODS: In order to address this hypothesis in vitro, we isolated and cultured porcine podocytes and ECs from GalTKO alone, human CD47 (hCD47)/hCD55 expressing transgenic (Tg) GalTKO swine, and GalTKO hCD46/hCD55 Tg swine along with baboon or human macrophages. RESULTS: We found that baboon macrophages phagocytosed porcine ECs in a similar manner to human macrophages, and this response was significantly reduced when porcine ECs and podocytes expressed hCD47/hCD55 but not hCD46/hCD55 without hCD47. Furthermore, masking hCD47 by anti-hCD47 antibody on hCD47/hCD55Tg ECs restored phagocytosis. These results are consistent with the hypothesis that CD47 incompatibility plays an important role in promoting macrophage phagocytosis of endogenous cells from the transplanted kidney. CONCLUSIONS: The similar levels of phagocytosis of porcine cells by baboon and human macrophages suggest that the expression of hCD47Tg on glomerular cells in donor porcine kidneys may prove to be a key strategy for preventing proteinuria following kidney xenotransplantation in a pig-to-human as well as a pig-to-baboon model.

A case of emergent operation for a life-threatening infectious mediastinal cyst.

PURPOSE: Congenital mediastinal cysts are an uncommon but important diagnostic group. Most of these cysts are benign and asymptomatic in adults. However, some of them are clinically problematic due to the compression of neighboring organs, infection, or perforation. CASE PRESENTATION: A 20-year-old man presented with severe dyspnea. Imaging revealed a mediastinal cyst in the subcarinal space compressing his right pulmonary artery and airway, which was later diagnosed as a bronchogenic cyst. Due to quick symptom exacerbation, emergent cyst wall fenestration was performed through video-assisted thoracic surgery with "stand-by" extracorporeal membrane oxygenation. Complete cyst resection was difficult owing to adhesion of the cyst to the surrounding organs. The symptoms immediately resolved after surgery and the postoperative course was uneventful. CONCLUSION: Mediastinal bronchogenic cysts with life-threatening complications are rarely reported in adults. However, this case was life-threatening due to airway and vascular compression; emergent surgical care should be considered in such cases.

Successful treatment based on molecular biological assessment of invasive anaplastic lymphoma kinase-positive inflammatory myofibroblastic tumor of the lung.

BACKGROUND: Inflammatory myofibroblastic tumor (IMT) of the lung is rare. This disease often shows neoplastic features with anaplastic lymphoma kinase positiveness as well as inflammatory features, such as steroid-responsive immunoglobulin G4 (IgG4)-related sclerosing disease. Since many cases have been reported as advanced, various treatment strategies should be considered based on clinical and biological features of each case. CASE PRESENTATION: We report a 49-year-old male with IMT, which seemed invading the left atrium from preoperative imaging modalities. Serological and pathological examinations from the biopsy specimen revealed high expression of anaplastic lymphoma kinase expression in the tumor. On the other hand, IgG4/IgG ration in the tumor was small, where a therapeutic effect of steroid was not expected, leading to surgical treatment rather than a steroid administration. The tumor was completely resected en bloc with the right lower lobe of the lung and a part of the left atrium. The postoperative course of the patient was uneventful. The patient has remained recurrence free over 5 years from the surgery. CONCLUSION: In this case, preoperative biological assessment prior to the treatment led to a good clinical course. We believe that molecular biological examination is important in the determination of treatment strategy for this rare disease as well as imaging modalities.

Adipose-derived mesenchymal stem cells attenuate rejection in a rat lung transplantation model.

BACKGROUND: Immunosuppression following lung transplantation is a key aspect to the graft's survival. However, the well-known complications that are caused by immunosuppressive regimens present an opportunity to study ways to minimize the usage of these drugs. Recently, a promising discovery has been made pertaining to the immunomodulatory effects of adipose tissue-derived mesenchymal stem cells (ADMSCs) through their secretion of hepatocyte growth factor. In the hopes of mitigating the adverse effects of standard immunosuppressive regimens, our study aims to investigate the effects of ADMSCs on the immune response utilizing a rat lung transplantation model. METHODS: Each rat's own ADMSCs were intravenously administered immediately after orthotopic left lung transplantation. The experimental subjects were divided into four groups: 1) control group (group C) was administered no treatment following transplantation; 2) ADMSC group (group A), administered a single intravenous injection of ADMSCs following transplantation; 3) tacrolimus group (group T), administered tacrolimus (0.5 mg/kg) every 24 h following transplantation; and 4) ADMSC and tacrolimus group (AT group) administered a single intravenous injection of ADMSCs in combination with tacrolimus every 24 h following transplantation. RESULTS: The histologically proven rejection grade in group AT was significantly lower than that in group T. The serum levels of hepatocyte growth factor and the expression of cMet in group AT accompanied by low CD40 expression were also significantly higher than those of the lung grafts of group T. CONCLUSIONS: These results suggest that co-administration of ADMSCs with tacrolimus is a beneficial therapeutic approach in lung transplantation.

Upregulation of CD80 on glomerular podocytes plays an important role in development of proteinuria following pig-to-baboon xeno-renal transplantation - an experimental study.

We have previously reported that co-transplantation of the kidney with vascularized donor thymus from α-1,3-galactosyltransferase gene knockout pigs with an anti-CD154 with rituximab-based regimen led to improved xenograft survival in baboons with donor-specific unresponsiveness. However, nephrotic syndrome emerged as a complication in which the glomeruli showed mild mesangial expansion with similarities to minimal change disease (MCD) in humans. Since MCD is associated with CD80 expression in glomeruli and elevated urinary excretion, we evaluated a potential role for CD80 in xenograft nephropathy. Study 1 confirmed high urinary CD80 excretion in nephrotic animals with renal xenografts showing CD80 expression in glomeruli. In Study 2, baboons receiving xenografts received CTLA4-Ig once a week from the second postoperative week or no CTLA4-Ig. The non-CTLA4-Ig group developed severe proteinuria with modest mesangial expansion with high urinary excretion of CD80 and documented CD80 expression in glomerular podocytes. All of the recipients in non-CTLA4-Ig groups had to be euthanized before POD 60. In contrast, CTLA4-Ig group showed a marked reduction in proteinuria and survived significantly longer, up to 193 days. These results demonstrate that anti-CD80 targeted therapy represents a promising strategy for reduction of proteinuria following renal xeno-transplantation with improved survival.

Remaining Physiological Barriers in Porcine Kidney Xenotransplantation: Potential Pathways behind Proteinuria as well as Factors Related to Growth Discrepancies following Pig-to-Kidney Xenotransplantation.

Considerable shortages in the supply of available organs continue to plague the field of solid organ transplantation. Despite changes in allocation, as well as the utilization of extended criteria and living donors, the number of patients waiting for organs continues to grow at an alarming pace. Xenotransplantation, cross-species solid organ transplantation, offers one potential solution to this dilemma. Previous extensive research dedicated to this field has allowed for resolution of xenograft failure due to acute rejection, leaving new areas of unresolved challenges as barriers to success in large animal models. Specific to kidney xenotransplantation, recent data seems to indicate that graft compromise can occur due to discrepancies in growth between breeds of donors and significant proteinuria leading to nephrotic syndrome in the recipient. Given these potential limitations, herein, we review potential pathways behind proteinuria, as well as potential causative factors related to growth discrepancies. Control of both of these has the potential to allow xenotransplantation to become clinically applicable in an effort to resolve this organ shortage crisis.