Recipient Tissue Research Articles

Targeting glycolytic reprogramming by tsRNA-0032 for treating pathological lymphangiogenesis

Lymphangiogenesis is vital for tissue fluid homeostasis, immune function, and lipid absorption. Abnormal lymphangiogenesis has been implicated in several diseases such as cancers, inflammatory, and autoimmune diseases. In this study, we elucidate the role of tsRNA-0032 in lymphangiogenesis and its molecular mechanism. tsRNA-0032 expression is significantly decreased in corneal suture model and human lymphatic endothelial cell (HLEC) model under inflammatory condition. Overexpression of tsRNA-0032 exerts anti-lymphangiogenic effects by inhibiting HLEC proliferation, migration, and tube formation. Moreover, overexpression of tsRNA-0032 inhibits suture-induced corneal lymphangiogenesis. tsRNA-0032 is mainly located in the cytoplasm and interacts with Ago2 protein. Overexpression of tsRNA-0032 reduces ATP production and decreases pyruvate and lactate levels by targeting PKM2, a key enzyme in glycolysis. This regulation of glycolysis alters cellular energy and metabolic balance in HLECs, contributing to anti-lymphangiogenic effects. Clinical data reveals that tsRNA-0032 levels are significantly reduced in corneal tissues of transplant recipients compared to donors, while PKM2 expression is elevated, highlighting the clinical relevance of tsRNA-0032/PKM2 axis in corneal lymphangiogenesis. This study offers new insights into the regulation of lymphangiogenesis and presents potential therapeutic targets for lymphangiogenesis-related diseases.

Chronic Graft-versus-host Disease: Immune Insights, Therapeutic Advances, and Parallels for Solid Organ Transplantation.

Chronic graft-versus-host disease remains a frequent and morbid outcome of allogeneic hematopoietic cell transplantation, in which the donor-derived immune system attacks healthy recipient tissue. Preceding tissue damage mediated by chemoradiotherapy and alloreactive T cells compromise central and peripheral tolerance mechanisms, leading to aberrant donor T cell and germinal center B cell differentiation, culminating in pathogenic macrophage infiltration and differentiation in a target tissue, with ensuant fibrosis. This process results in a heterogeneous clinical syndrome with significant morbidity and mortality, frequently requiring prolonged therapy. In this review, we discuss the processes that interrupt immune tolerance, the subsequent clinical manifestations, and new Food and Drug Administration-approved therapeutic approaches that have been born from a greater understanding of disease pathogenesis in preclinical systems, linking to parallel processes following solid organ transplantation.

Prognostic Significance of Biointegration at the Optic-Cornea Joint in Keratoprosthesis Implantation.

The purpose of this study was to characterize the morphological and immunological aspects of biointegration at the optic-cornea joint of a second-generation synthetic corneal device. The initial prototype, single-piece optic-skirt configuration, is constructed from compact and flexible perfluoroalkoxy alkane with porous expanded polytetrafluoroethylene (ePTFE) overlying the skirt to allow skirt-cornea biointegration. The second-generation version was modified to add ePTFE around the optic wall to allow optic-cornea biointegration. Initial and amended second-generation devices were implanted into healthy rabbit eyes. Clinical examination, anterior segment optical coherence tomography, light microscopy, and immunofluorescence studies were performed to assess structural integrity and determine molecular signatures indicative of inflammation and tissue remodeling between the 2 prototypes. Recipient eyes with both device versions showed no epithelial defects or tissue retraction at 3 months postoperatively. Optical coherence tomography images demonstrated no appreciable perioptic space with either prototype. Histopathology of the initial device demonstrated lack of stromal adhesion at the optic-cornea joint with epithelium filling the perioptic space. Second-generation devices demonstrated full sealing of the recipient stroma along the optic stem. Although the routine histopathology did not demonstrate inflammatory cells in the recipient cornea with either device, immunohistochemistry stains demonstrated quiescent phenotype of stromal and epithelial cells only in the second-generation devices. Biointegration between the synthetic corneal device and recipient tissue at the optic-cornea joint seems to avert inflammation and may help prevent sterile tissue lysis and prolong retention.

The effect of human umbilical cord-derived mesenchymal stem cell transplantation on the reparative properties of muscle-aponeurotic defect reconstruction in the anterior abdominal wall of rats

Postoperative ventral hernias represent a significant challenge in modern surgery, arising as complications following abdominal operations due to weakness or defects in the musculoaponeurotic structure of the anterior abdominal wall. Mesenchymal stem cells (MSCs) possess high reparative potential due to their paracrine ability to stimulate the regeneration of damaged recipient tissues. Objective. To investigate the effect of intraperitoneal transplantation of human umbilical cord-derived MSCs on the regeneration of muscle fibers in the area of musculoaponeurotic defect repair in the anterior abdominal wall of rats. Materials and Methods. A surgical model of a musculoaponeurotic defect (2 cm in diameter) in the anterior abdominal wall was created in 72 white rats. Animals were divided into four groups based on the method of defect correction: 1) repair with autologous tissues; 2) repair with autologous tissues combined with MSC injection; 3) repair using a polypropylene mesh; 4) repair using a polypropylene mesh combined with MSC injection. Human umbilical cord-derived MSCs were isolated using enzymatic methods, validated by flow cytometry for surface marker expression, and administered intraperitoneally at a dose of 1 million cells per kilogram of body weight. On the 10th and 30th days, histological analysis of tissue samples from the repair site was conducted, assessing the presence of granulation tissue, collagen fibers, newly formed connective tissue, and cellular infiltration. Morphometric comparisons included the relative areas of granulation and fibrous reticular tissue, microcirculatory vessels, and counts of neutrophilic leukocytes, lymphohistiocytic elements, and fibroblasts per square millimeter of section. Results. In Group 1, the repair area demonstrated loose connective tissue rich in fibroblasts and histiocytes. In Group 2, a significantly reduced cellular reaction was observed, along with the formation of denser connective tissue bundles; transverse striation of muscle fibers was more clearly visualized at the sites of damage. On day 10, the granulation tissue area was 34.6% smaller, and the microcirculatory vessel area was 15.9% smaller compared to Group 1, and 28.1% and 57.2% smaller, respectively, compared to Group 3. In Group 3, granulation tissue formed at sites of necrosis and muscle fiber destruction. The best results were observed with the combination of polypropylene mesh and MSCs, where complete resolution of the inflammatory response and scar tissue formation was recorded. In Group 4, on day 10, the granulation tissue area was 2.5 times smaller than in Group 1 and 1.3 times smaller than in Group 2. The relative area of microcirculatory vessels was 1.8 times smaller than in Group 1 and 1.3 times smaller than in Group 2, whereas the fibrous reticular tissue area was 3.2 and 1.2 times larger, respectively. By day 30, granulation tissue, microcirculatory vessels, and leukocytes were no longer detected. The fibrous reticular tissue area was the largest among all groups at this time point. Conclusion. Intraperitoneal transplantation of human umbilical cord-derived MSCs in conjunction with polypropylene mesh repair of musculoaponeurotic defects in the anterior abdominal wall of rats improves regeneration at the defect site and promotes faster healing.

Novel coenzyme Q6 genetic variant increases susceptibility to pneumococcal disease.

Acute lower respiratory tract infection (ALRI) remains a major worldwide cause of childhood mortality, compelling innovation in prevention and treatment. Children in Papua New Guinea (PNG) experience profound morbidity from ALRI caused by Streptococcus pneumoniae. As a result of evolutionary divergence, the human PNG population exhibits profound genetic variation and diversity. To address unmet health needs of children in PNG, we tested whether genetic variants increased ALRI morbidity. Whole-exome sequencing of a pilot child cohort identified homozygosity for a novel single-nucleotide variant (SNV) in coenzyme Q6 (COQ6) in cases with ALRI. COQ6 encodes a mitochondrial enzyme essential for biosynthesis of ubiquinone, an electron acceptor in the electron transport chain. A significant association of SNV homozygosity with ALRI was replicated in an independent ALRI cohort (P = 0.036). Mice homozygous for homologous mouse variant Coq6 exhibited increased mortality after pneumococcal lung infection, confirming causality. Bone marrow chimeric mice further revealed that expression of variant Coq6 in recipient (that is, nonhematopoietic) tissues conferred increased mortality. Variant Coq6 maintained ubiquinone biosynthesis, while accelerating metabolic remodeling after pneumococcal challenge. Identification of this COQ6 variant provides a genetic basis for increased pneumonia susceptibility in PNG and establishes a previously unrecognized role for the enzyme COQ6 in regulating inflammatory-mediated metabolic remodeling.

Molecular modifications to mitigate oxidative stress and improve red blood cell storability.

The development of red blood cell (RBC) storage lesion during hypothermic storage has long posed challenges for blood transfusion efficacy. These alterations are primarily driven by oxidative stress, concern both structural and biochemical aspects of RBCs, and affect their interactions with the recipient's tissues post-transfusion. Efforts to counteract these effects focus on improving the antioxidant capacity within stored RBCs, reducing oxygen exposure, and scavenging harmful molecules that accumulate during storage. Various supplements, such as ascorbic acid, N-acetylcysteine, polyphenolic compounds, and specific metabolites have shown the potential to improve RBC quality by reducing oxidative lesions and lysis phenomena, and enhancing antioxidant, energy, or proteostasis networks. Accordingly, anaerobic storage has emerged as a promising strategy, demonstrating improved RBC storability and recovery in both animal models and preliminary human studies. Finally, targeted scavenging of harmful storage-related phenotypes and molecules, like removal signals, oxidized proteins, and extracellular hemoglobin, while not so studied, also has the potential to benefit both the unit and the patient in need. Omics technologies have aided a lot in these endeavors by revealing biomarkers of superior storability and, thus, potential novel supplementation strategies. Nonetheless, while the so far examined storage modifications show significant promise, there are not many post-transfusion studies (either in vitro, in animal models, or humans) to evaluate RBC efficacy in the transfusion setting. Looking ahead, the future of blood storage and transfusion will likely depend on the optimization of these interventions to extend the shelf-life and quality of stored RBCs, as well as their therapeutic outcome.

Single-cell transcriptome analysis reveals atypical monocytes circulating ahead of acute graft-versus-host disease clinical onset.

Acute graft-versus-host disease (aGVHD) represents the rejection of the recipient's skin, gut, and liver tissues of an allogeneic hematopoietic stem cell transplantation (HSCT) by the donor T-cells. The onset of aGVHD is often rapid and its evolution is unpredictable. We undertook the single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) collected before aGVHD clinical onset in three patients and from one patient afterward. We used four HSCT recipients who remained free of aGVHD as controls. This analysis unveiled the presence of particular subpopulations of circulating monocytes and cytotoxic T cells (CTLs) in pre-aGVHD samples up to 18 days before clinical disease. These pre-aGVHD monocytes were characterized by an upregulation of the M2 polarity marker CD163 and the transmembrane protein SIGLEC1/CD169. At the same time, their CTL counterparts stood out for the upregulation of the CXCL10 receptor CXCR3 and the antigenic stimulation marker CD70. The occurrence of CD163/SIGLEC1 co-expressing monocytes upstream of aGVHD onset was validated using transcriptomic data from an independent cohort and by flow cytometry in additional blood samples. These findings point to potential early diagnostic tools and preventive therapeutic strategies for aGVHD.

Использование имплантатов из пористого никелида титана в замещении тотальных дефектов скуловой кости и дуги

Summary. The aim of the study is to increase the efficiency of total replacement of the zygomatic bone and arch by developing a new medical technology using shape memory materials. Materials and methods of the study. Research materials – technologies using shape memory materials. Research method – development of an endoprosthesis of the zygomatic bone and arch. Research results and their analysis. Analysis of the research results showed: – the use of endoprostheses made of porous titanium nickelide in accordance with the anatomical features of the affected organ makes it possible to fully restore the lost anatomical and functional capabilities of the facial skull; – coating the endoprosthesis frame with textile titanium nickelide, in addition to improving the conditions for the interaction of the implant with the recipient tissues, allows to fully compensate for the insufficiency of the soft tissue component of the face; – fixing structures with a shape memory effect are easy to use, do not require significant time costs and provide stable fixation of the endoprosthesis with bone structures.

Human uncultured adipose-derived stromal vascular fraction shows therapeutic potential against osteoarthritis in immunodeficient rats via direct effects of transplanted M2 macrophages

BackgroundThe uncultured adipose-derived stromal vascular fraction (SVF), consisting of adipose-derived stromal cells (ADSCs), M2 macrophages (M2Φ) and others, has shown therapeutic potential against osteoarthritis (OA), however, the mechanisms underlying its therapeutic effects remain unclear. Therefore, this study investigated the effects of the SVF on OA in a human-immunodeficient rat xenotransplantation model.MethodsOA model was induced in the knees of female immunodeficient rats by destabilization of the medial meniscus. Immediately after the surgery, human SVF (1 × 105), ADSCs (1 × 104), or phosphate buffered saline as a control group were transplanted into the knees. At 4 and 8 weeks postoperatively, OA progression and synovitis were analyzed by macroscopic and histological analyses, and the expression of collagen II, SOX9, MMP-13, ADAMTS-5, F4/80, CD86 (M1), CD163 (M2), and human nuclear antigen (hNA) were evaluated immunohistochemically. In vitro, flow cytometry was performed to collect CD163-positive cells as M2Φ from the SVF. Chondrocyte pellets (1 × 105) were co-cultured with SVF (1 × 105), M2Φ (1 × 104), and ADSCs (1 × 104) or alone as a control group, and the pellet size was compared. TGF-β, IL-10 and MMP-13 concentrations in the medium were evaluated using enzyme-linked immunosorbent assay.ResultsIn comparison with the control and ADSC groups, the SVF group showed significantly slower OA progression and less synovitis with higher expression of collagen II and SOX9, lower expression of MMP-13 and ADAMTS-5, and lower F4/80 and M1/M2 ratio in the synovium. Only the SVF group showed partial expression of hNA-, CD163-, and F4/80-positive cells in the rat synovium. In vitro, the SVF, M2Φ, ADSC and control groups, in that order, showed larger pellet sizes, higher TGF-β and IL-10, and lower MMP-13 concentrations.ConclusionsThe M2Φ in the transplanted SVF directly affected recipient tissue, enhancing the secretion of growth factors and chondrocyte-protecting cytokines, and partially improving chondrocytes and joint homeostasis. These findings indicate that the SVF is as an effective option for regenerative therapy for OA, with mechanisms different from those of ADSCs.

Recipient tissue microenvironment determines developmental path of intestinal innate lymphoid progenitors

Innate lymphoid cells (ILCs) are critical in maintaining tissue homeostasis, and during infection and inflammation. Here we identify, by using combinatorial reporter mice, a rare ILC progenitor (ILCP) population, resident to the small intestinal lamina propria (siLP) in adult mice. Transfer of siLP-ILCP into recipients generates group 1 ILCs (including ILC1 and NK cells), ILC2s and ILC3s within the intestinal microenvironment, but almost exclusively group 1 ILCs in the liver, lung and spleen. Single cell gene expression analysis and high dimensional spectral cytometry analysis of the siLP-ILCPs and ILC progeny indicate that the phenotype of the group 1 ILC progeny is also influenced by the tissue microenvironment. Thus, a local pool of siLP-ILCP can contribute to pan-ILC generation in the intestinal microenvironment but has more restricted potential in other tissues, with a greater propensity than bone marrow-derived ILCPs to favour ILC1 and ILC3 production. Therefore, ILCP potential is influenced by both tissue of origin and the microenvironment during development. This may provide additional flexibility during the tuning of immune reactions.

A Drosophila model for mechanistic investigation of tau protein spread.

Brain protein aggregates are a hallmark of neurodegenerative disease. Previous work indicates that specific protein components of these aggregates are toxic, including tau (encoded by MAPT) in Alzheimer's disease and related tauopathies. Increasing evidence also indicates that these toxic proteins traffic between cells in a prion-like fashion, thereby spreading pathology from one brain region to another. However, the mechanisms involved in trafficking are poorly understood. We therefore developed a transgenic Drosophila model to facilitate rapid evaluation of candidate tau trafficking modifiers. Our model uses the bipartite Q system to drive co-expression of tau and GFP in the fly eye. We found age-dependent spread of tau into the brain, represented by detection of tau, but not of GFP. We also found that tau trafficking was attenuated upon inhibition of the endocytic factor dynamin (encoded by shi) or knockdown of glycogen synthase kinase-3β (GSK-3β, encoded by sgg). Further work revealed that dynamin promoted tau uptake in recipient tissues, whereas GSK-3β appeared to promote tau spread via direct phosphorylation of tau. Our robust and flexible system will promote the identification of tau-trafficking components involved in the pathogenesis of neurodegenerative diseases.

Analyzing Porcine Corneal Xenograft Compatibility: In Silico Insights on Graft Outcomes

Background: Corneal transplantation faces significant challenges due to the shortage in donor corneas. Porcine corneas have emerged as a potential solution due to their similarities in biomechanical properties with pigs, yet xenoimmune rejection poses an obstacle to their efficacy. Methods: In this study, in silico methods were employed to analyze the compatibility of porcine corneal xenografts, focusing on two key aspects: the comparison of corneal matrix proteins and investigation of the immunological mediators and pathways involved in corneal graft rejection. The amino acid sequences of the fourteen (14) most abundant proteins in the corneal matrix were compared to determine their structural and functional differences. The primary amino acid structures and compositions, theoretical pI, and grand average of hydropathicity were determined and compared between the two species. Results: In graft performance, similarities and differences between the donor and recipient tissues influence the success of transplantation. When the proteins closely resemble each other, in terms of structural characteristics and biochemical properties, the host’s immune system is less likely to recognize the tissue as foreign. The immunological mediators and pathways involved in corneal graft rejection were investigated, elucidating the mechanisms underlying xenograft incompatibility. Based on the results generated from STRING, the specific groups of molecules that are involved in the immune-mediated rejection process are costimulatory molecules, cytokines, immune checkpoint molecules, apoptosis regulators, cell adhesion molecules, growth factors, neuropeptides and hormones, certain receptors, the cytotoxic molecule GZMA, and the chemokine CCL5. Conclusions: The results of this study establish that the porcine cornea has a high suitability for corneal xenotransplantation into humans but requires immune-based therapeutic interventions to increase graft acceptance.

The Myofibroblast Fate of Therapeutic Mesenchymal Stromal Cells: Regeneration, Repair, or Despair?

Mesenchymal stromal cells (MSCs) can be isolated from various tissues of healthy or patient donors to be retransplanted in cell therapies. Because the number of MSCs obtained from biopsies is typically too low for direct clinical application, MSC expansion in cell culture is required. However, ex vivo amplification often reduces the desired MSC regenerative potential and enhances undesired traits, such as activation into fibrogenic myofibroblasts. Transiently activated myofibroblasts restore tissue integrity after organ injury by producing and contracting extracellular matrix into scar tissue. In contrast, persistent myofibroblasts cause excessive scarring-called fibrosis-that destroys organ function. In this review, we focus on the relevance and molecular mechanisms of myofibroblast activation upon contact with stiff cell culture plastic or recipient scar tissue, such as hypertrophic scars of large skin burns. We discuss cell mechanoperception mechanisms such as integrins and stretch-activated channels, mechanotransduction through the contractile actin cytoskeleton, and conversion of mechanical signals into transcriptional programs via mechanosensitive co-transcription factors, such as YAP, TAZ, and MRTF. We further elaborate how prolonged mechanical stress can create persistent myofibroblast memory by direct mechanotransduction to the nucleus that can evoke lasting epigenetic modifications at the DNA level, such as histone methylation and acetylation. We conclude by projecting how cell culture mechanics can be modulated to generate MSCs, which epigenetically protected against myofibroblast activation and transport desired regeneration potential to the recipient tissue environment in clinical therapies.

Dual-color FISH analyses of xenogeneic human fibroblast sheets transplanted to repair lung pleural defects in an immunocompromised rat model

BackgroundPulmonary air leaks (PALs) due to visceral pleura injury during surgery is frequently observed after pulmonary resections and the complication is difficult to avoid in thoracic surgery. The development of postoperative PALs is the most common cause of prolonged hospitalization. Previously, we reported that PALs sealants using autologous dermal fibroblast sheets (DFSs) harvested from temperature-responsive culture dishes successfully closed intraoperative PALs during lung resection.ObjectiveIn this study, we investigated the fate of human DFSs xenogenetically transplanted onto lung surfaces to seal PALs of immunocompromised rat. Dual-color FISH analyses of human fibroblast was employed to detect transplantation human cells on the lung surface.ResultsOne month after transplantation, FISH analyses revealed that transplanted human fibroblasts still composed a sheet-structure, and histology also showed that beneath the sheet’s angiogenesis migrating into the sheets was observed from the recipient tissues. FISH analyses revealed that even at 3 months after transplantation, the transplanted human fibroblasts still remained in the sheet. Dual-color FISH analyses of the transplanted human fibroblasts were sparsely present as a result of the cells reaching the end of their lifespan, the cells producing extracellular matrix, and remained inside the cell sheet and did not invade the lungs of the host.ConclusionsDFS-transplanted human fibroblasts showed that they are retained within cell sheets and do not invade the lungs of the host.

Depletion of donor dendritic cells ameliorates immunogenicity of both skin and hind limb transplants.

Acute cellular rejection remains a significant obstacle affecting successful outcomes of organ transplantation including vascularized composite tissue allografts (VCA). Donor antigen presenting cells (APCs), particularly dendritic cells (DCs), orchestrate early alloimmune responses by activating recipient effector T cells. Employing a targeted approach, we investigated the impact of donor-derived conventional DCs (cDCs) and APCs on the immunogenicity of skin and skin-containing VCA grafts, using mouse models of skin and hind limb transplantation. By post-transplantation day 6, skin grafts demonstrated severe rejections, characterized by predominance of recipient CD4 T cells. In contrast, hind limb grafts showed moderate rejection, primarily infiltrated by CD8 T cells. Notably, the skin component exhibited heightened immunogenicity when compared to the entire VCA, evidenced by increased frequencies of pan (CD11b-CD11c+), mature (CD11b-CD11c+MHCII+) and active (CD11b-CD11c+CD40+) DCs and cDC2 subset (CD11b+CD11c+ MHCII+) in the lymphoid tissues and the blood of skin transplant recipients. While donor depletion of cDC and APC reduced frequencies, maturation and activation of DCs in all analyzed tissues of skin transplant recipients, reduction in DC activities was only observed in the spleen of hind limb recipients. Donor cDC and APC depletion did not impact all lymphocyte compartments but significantly affected CD8 T cells and activated CD4 T in lymph nodes of skin recipients. Moreover, both donor APC and cDC depletion attenuated the Th17 immune response, evident by significantly reduced Th17 (CD4+IL-17+) cells in the spleen of skin recipients and reduced levels of IL-17E and lymphotoxin-α in the serum samples of both skin and hind limb recipients. In conclusion, our findings underscore the highly immunogenic nature of skin component in VCA. The depletion of donor APCs and cDCs mitigates the immunogenicity of skin grafts while exerting minimal impact on VCA.

Characterization of heterogeneous skin constructs for full thickness skin regeneration in murine wound models

An autologous heterogeneous skin construct (AHSC) has been developed and used clinically as an alternative to traditional skin grafting techniques for treatment of cutaneous defects. AHSC is manufactured from a small piece of healthy skin in a manner that preserves endogenous regenerative cellular populations. To date however, specific cellular and non-cellular contributions of AHSC to the epidermal and dermal layers of closed wounds have not been well characterized given limited clinical opportunity for graft biopsy following wound closure. To address this limitation, a three-part mouse full-thickness excisional wound model was developed for histologic and macroscopic graft tracing. First, fluorescent mouse-derived AHSC (mHSC) was allografted onto non-fluorescent recipient mice to enable macroscopic and histologic time course evaluation of wound closure. Next, mHSC-derived from haired pigmented mice was allografted onto gender- and major histocompatibility complex (MHC)-mismatched athymic nude mouse recipients. Resulting grafts were distinguished from recipient murine skin via immunohistochemistry. Finally, human-derived AHSC (hHSC) was xenografted onto athymic nude mice to evaluate engraftment and hHSC contribution to wound closure. Experiments demonstrated that mHSC and hHSC facilitated wound closure through production of viable, proliferative cellular material and promoted full-thickness skin regeneration, including hair follicles and glands in dermal compartments. This combined macroscopic and histologic approach to tracing AHSC-treated wounds from engraftment to closure enabled robust profiling of regenerated architecture and further understanding of processes underlying AHSC mechanism of action. These models may be applied to a variety of wound care investigations, including those requiring longitudinal assessments of healing and targeted identification of donor and recipient tissue contributions.

Donor regulatory T cells rapidly adapt to recipient tissues to control murine acute graft-versus-host disease

The adoptive transfer of regulatory T cells is a promising strategy to prevent graft-versus-host disease after allogeneic bone marrow transplantation. Here, we use a major histocompatibility complex-mismatched mouse model to follow the fate of in vitro expanded donor regulatory T cells upon migration to target organs. Employing comprehensive gene expression and repertoire profiling, we show that they retain their suppressive function and plasticity after transfer. Upon entering non-lymphoid tissues, donor regulatory T cells acquire organ-specific gene expression profiles resembling tissue-resident cells and activate hallmark suppressive and cytotoxic pathways, most evidently in the colon, when co-transplanted with graft-versus-host disease-inducing conventional T cells. Dominant T cell receptor clonotypes overlap between organs and across recipients and their relative abundance correlates with protection efficacy. Thus, this study reveals donor regulatory T cell selection and adaptation mechanisms in target organs and highlights protective features of Treg to guide the development of improved graft-versus-host disease prevention strategies.

Development of a Mouse Experimental System for the In Vivo Characterization of Bioengineered Adipose-Derived Stromal Cells.

Human adipose-derived stromal cells (ADSCs) are an important resource for cell-based therapies. However, the dynamics of ADSCs after transplantation and their mechanisms of action in recipients remain unclear. Herein, we generated genetically engineered mouse ADSCs to clarify their biodistribution and post-transplantation status and to analyze their role in recipient mesenchymal tissue modeling. Immortalized ADSCs (iADSCs) retained ADSC characteristics such as stromal marker gene expression and differentiation potential. iADSCs expressing a fluorescent reporter gene were seeded into biocompatible nonwoven fabric sheets and transplanted into the dorsal subcutaneous region of neonatal mice. Transplanted donor ADSCs were distributed as CD90-positive stromal cells on the sheets and survived 1 month after transplantation. Although accumulation of T lymphocytes or macrophages inside the sheet was not observed with or without donor cells, earlier migration and accumulation of recipient blood vascular endothelial cells (ECs) inside the sheet was observed in the presence of donor cells. Thus, our mouse model can help in studying the interplay between donor ADSCs and recipient cells over a 1-month period. This system may be of value for assessing and screening bioengineered ADSCs in vivo for optimal cell-based therapies.

Design of a Multiparametric Perfusion Bioreactor System for Evaluating Sub-Normothermic Preservation of Rat Abdominal Wall Vascularized Composite Allografts.

Static cold storage (SCS), the current clinical gold standard for organ preservation, provides surgeons with a limited window of time between procurement and transplantation. In vascularized composite allotransplantation (VCA), this time limitation prevents many viable allografts from being designated to the best-matched recipients. Machine perfusion (MP) systems hold significant promise for extending and improving organ preservation. Most of the prior MP systems for VCA have been built and tested for large animal models. However, small animal models are beneficial for high-throughput biomolecular investigations. This study describes the design and development of a multiparametric bioreactor with a circuit customized to perfuse rat abdominal wall VCAs. To demonstrate its concept and functionality, this bioreactor system was employed in a small-scale demonstrative study in which biomolecular metrics pertaining to graft viability were evaluated non-invasively and in real time. We additionally report a low incidence of cell death from ischemic necrosis as well as minimal interstitial edema in machine perfused grafts. After up to 12 h of continuous perfusion, grafts were shown to survive transplantation and reperfusion, successfully integrating with recipient tissues and vasculature. Our multiparametric bioreactor system for rat abdominal wall VCA provides an advanced framework to test novel techniques to enhance normothermic and sub-normothermic VCA preservations in small animal models.

Fat transfer principles and applications in plastic surgery: a literature review

Fat transfer of fat grafting is a renowned technique in plastic surgery, in which harvested fat tissue is injected beneath the skin into part of the body to be reconstructed. The fat transfer technique is the most popular choice for reconstructive and cosmetic procedures due to its low immunogenicity, low cost, and ease of access. In cosmetic, reconstructive plastic surgery, the fat transfer procedure is done by moving fat tissue from one body part to another body part. It consists of five main procedures: harvesting fat tissue, processing fat tissue, determining the recipient location, transferring or grafting fat tissue, and retaining or surviving the graft/fat transfer results. Procedures for fat transfer are typically done on the face, breasts, and buttocks. Fat transfer can lead to many consequences, such as skin issues, hematomas, infections, seromas, and even fatal fat emboli. This literature review aims to explain the principles of fat transfer and their applications in plastic surgery.