Biology subjects

Hematti, P.

Publications and source records attributed to Hematti, P..

6 recordsLinked to original sources

bioRxiv2025

Autofluorescence imaging reveals the impact of cryopreservation on T cell metabolism and activation response

Cryopreservation or the process of freezing cells is a cornerstone of most cell therapy protocols. Optimization of cryopreservation protocols and cryoprotectant agents to improve cell viability and functionality is under further investigation. However, the impact of cryopreservation on cellular metabolism and function immediately post-thaw is not fully understood. Here, we used label-free, non-invasive optical metabolic imaging (OMI) of NAD(P)H and FAD to characterize the activation response of frozen T cells from healthy donors and lymphoma patients post-thaw. Using OMI, we identified significant metabolic shift, along with delayed and diminished activation response in healthy donor T cells throughout the first 4.5 hours upon thawing. In cryopreserved peripheral T cells from lymphoma patients in our bispecific CD19/CD20 CAR T therapy clinical trial, OMI could identify early metabolic stress and allowed gating of metabolically-fit cells associated with post-thaw viability. Notably, in our pilot study, only metabolically-fit T cells from complete responders exhibited metabolic responses to activating stimuli within the first 4.5 hours post-thaw. Overall, our findings suggest that 4-5 hours post-thaw is a critical time window to assess the impact of cryopreservation and thawing, and support the potential of OMI to optimize cryopreservation protocols and evaluate patient T cell quality for cell therapy.

immunology↗

bioRxiv2023

Modulating Mesenchymal Stromal Cell Microenvironment Alters Exosome RNA Content and Ligament Healing Capacity

Although mesenchymal stromal cell (MSC) based therapies hold promise in regenerative medicine, their applications in clinical settings remain challenging due to issues such as immunocompatibility and cell stability. MSC-derived exosomes, small vesicles carrying various bioactive molecules, are a promising cell-free therapy to promote tissue regeneration. However, it remains unknown mainly regarding the ability to customize the content of MSC-derived exosomes, how alterations in the MSC microenvironment influence exosome content, and the effects of such modifications on healing efficiency and mechanical properties in tissue regeneration. In this study, we used an in vitro system of human MSC-derived exosomes and an in vivo rat ligament injury model to address these questions. We found a context-dependent correlation between exosomal and parent cell RNA content. Under native conditions, the correlation was moderate but heightened with microenvironmental changes. In vivo rat ligament injury model showed that MSC-derived exosomes increased ligament max load and stiffness. We also found that changes in the MSCs microenvironment significantly influence the mechanical properties driven by exosome treatment. Additionally, a link was identified between altered exosomal microRNA levels and expression changes in microRNA targets in ligaments. These findings elucidate the nuanced interplay between MSCs, their exosomes, and tissue regeneration. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/563485v2_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@2b45bborg.highwire.dtl.DTLVardef@ef2222org.highwire.dtl.DTLVardef@1a9f1f1org.highwire.dtl.DTLVardef@4b1ca2_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Differentiation of a CD4+/CD8αβ+ Double Positive T Cell Population From The CD8 Pool Is Sufficient To Mediate Graft-vs-Host Disease but not Graft-vs-Leukemia Effects

An important paradigm in allogeneic hematopoietic cell transplantations (allo-HCTs) is the prevention of graft-vs-host disease (GVHD) while preserving the graft-vs-leukemia (GVL) activity of donor T cells. From an observational clinical study of adult allo-HCT recipients, we identified a CD4+/CD8+ double positive T cell (DPT) population, not present in starting grafts, whose presence was predictive of [≥] grade 2 GVHD. Using an established xenogeneic transplant model, we reveal that the DPT population develop from antigen stimulated CD8 T cells which become transcriptionally, metabolically and phenotypically distinct from single-positive CD4 and CD8 T cells. Isolated DPTs were sufficient to mediate xeno-GVHD pathology when re-transplanted into naive mice but provided no survival benefit when mice were challenged with a human B-ALL cell line. Overall, this study reveals human DPTs as a T cell population directly involved with GVHD pathology. One Sentence SummaryHuman CD4+/CD8+ double positive T cells (DPTs) mediate xenogeneic GVHD but possess limited GVL activity.

immunology↗

bioRxiv2021

Investigating the in vivo biodistribution of extracellular vesicles isolated from various human cell sources using positron emission tomography

Noninvasive imaging is a powerful tool for understanding the in vivo behavior of drug delivery systems and successfully translating promising platforms into the clinic. Extracellular vesicles (EVs), nano-sized vesicles with a lipid bilayer produced by nearly all cell types, are emerging platforms for drug delivery. To date, the biodistribution of EVs has been insufficiently investigated, particularly using nuclear imaging-based modalities such as positron emission tomography (PET). Herein, we developed positron-emitting radiotracers to investigate the biodistribution of EVs isolated from various human cell sources using PET imaging. Chelator conjugation did not impact EVs size and subsequent radiolabeling was found to be highly efficient and stable with Zr-89 (t1/2 = 78.4 h). In vivo tracking of EVs isolated from bone marrow-derived mesenchymal stromal cells (BMSCs EVs), primary human macrophages (M{phi} EVs), and a melanoma cell line (A375 EVs) were performed in immunocompetent ICR mice. Imaging studies revealed excellent in vivo circulation for all EVs, with a half-life of approximately 12 h. Significantly higher liver uptake was observed for M{phi} EVs, evidencing the tissue tropism of EV and highlighting the importance of carefully choosing EVs cell sources for drug delivery applications. Conversely, the liver, spleen, and lung uptake of the BMSC EVs and A375 EVs was relatively low. We also investigated the impact of immunodeficiency on the biodistribution of BMSC EVs using NSG mice. The spleen uptake drastically increased in NSG mice, which could confound results of therapeutic studies employing this mouse models. Lastly, PET imaging studies in a melanoma tumor model demonstrated efficient tumor uptake of BMSC EVs following intravenous injection. Overall, these imaging studies evidenced the potential of EVs as carriers to treat a variety of diseases, such as cancer or in regenerative medicine applications, and the necessity to understand EVs tropism to optimize their therapeutic deployment.

bioengineering↗

bioRxiv2021

MHC-matched allogeneic bone marrow transplant fails to eliminate SHIV-infected cells from ART-suppressed Mauritian cynomolgus macaques

BackgroundAllogeneic hematopoietic stem cell transplants (allo-HSCTs) dramatically reduce HIV reservoirs in antiretroviral therapy (ART) suppressed individuals. However, the mechanism(s) responsible for these post-transplant viral reservoir declines are not fully understood but may include pre-transplant conditioning regimens, ART-mediated protection of donor cells, and graft-versus-host (GvH) responses. Therefore, we modeled allo-HSCT in ART-suppressed simian-human immunodeficiency virus (SHIV)-infected Mauritian cynomolgus macaques (MCMs) to illuminate factors contributing to transplant-induced viral reservoir decay. ResultsWe infected four MCMs with CCR5-tropic SHIV162P3 and started ART 6-16 weeks post-infection (p.i.) to establish robust viral reservoirs. We maintained the MCMs on continuous ART during myeloablative conditioning with total body irradiation (TBI) and while transplanting allogeneic MHC-matched /{beta} T cell-depleted bone marrow cells. Post-transplant, we prophylactically treated the MCMs with cyclophosphamide and tacrolimus to prevent GvH disease (GvHD). The transplants produced ~85% whole blood donor chimerism without causing high-grade GvHD. Consequently, three MCMs had undetectable SHIV DNA in their peripheral blood mononuclear cells post-transplant. However, SHIV-harboring cells persisted in various tissues. We detected viral DNA in lymph node biopsies and terminal analyses of tissues between 38 and 62 days post-transplant. Further, we removed ART from one MCM at 63 days post-transplant, resulting in viral rebound within seven days and viral loads nearing 1x108 SHIV RNA copies/ml of plasma after treatment interruption. ConclusionsOur results indicate that myeloablative conditioning and maintaining ART through the peri-transplant period alone are insufficient for eradicating latent viral reservoirs early after allo-HSCTs. Furthermore, our findings suggest that extended ART and GvH responses may be necessary to substantially deplete viral reservoirs after allo-HSCTs.

immunology↗

bioRxiv2018

Versican Proteolysis Predicts Immune Effector Infiltration And Post-Transplant Survival In Myeloma

High-dose alkylator-based conditioning followed by autologous stem-cell transplantation (ASCT) is a therapeutic mainstay for eligible patients with multiple myeloma. However, post-transplant relapses are common and prognostic biomarkers are scarce. Relapses are characterized by the influx of regulatory myeloid cells and dysfunctional T effectors. We have shown that myeloma-infiltrating myeloid cells produce versican (VCAN), a large matrix proteoglycan with tolerogenic activities. VCAN proteolysis by a-disintegrin-and-metalloproteinase-with-thrombospondin-motifs (ADAMTS) proteases generates versikine, a bioactive fragment (\"matrikine\") that regulates Batf3-dendritic cells, known to control CD8+-attracting chemokine networks. Here we demonstrate that intense VCAN proteolysis predicts CD8+ infiltration post-transplant and paradoxically portends significantly inferior survival outcomes. Our data suggest that VCAN proteolysis promotes the influx of CD8+ effectors that are rendered overwhelmingly dysfunctional and/or frankly immunoregulatory (CD8+ Treg) at the tumor site. Thus, complex immunosuppressive circuits orchestrated through VCAN accumulation and turnover generate conditions favorable for myeloma tumor regrowth and point to a readily-assayed biomarker to identify the patients at risk for relapse and early death. The dismal outcomes associated with VCAN proteolysis may be rationally overcome through immunotherapies such as checkpoint inhibition (e.g., anti-TIGIT), tumor vaccines or anti-myeloid (e.g., anti-CSF-1R) approaches.

immunology↗