Perceived Needs Among Healthcare Providers Caring for Seriously Ill Adults Regarding Electronic Health Record Triggers for Palliative Care Referral.

Many healthcare facilities in the United States currently utilize electronic health record triggers to promote and facilitate palliative care referral. The purpose of this study was to explore perceived needs regarding electronic health record trigger criteria for palliative care referral among healthcare providers caring for seriously ill adult hospitalized patients in a teaching hospital in New York State. A qualitative descriptive approach was utilized with use of individual semistructured interviews. Braun and Clarke's Reflexive Thematic Analysis method was used to analyze data. Data analysis generated one overarching theme, I'm in Favor of an Electronic Health Record Automatic Trigger for Palliative Care , and three key themes, Build a Checklist Screening Tool Into Epic With Predefined Conditions and a Palliative Consult in the Admission Order Set , If Providers Call a Palliative Care Consult Sooner, We Give Patients a Better Quality of Life , and Providers Need to Be Aware of the Different Facets of What Palliative Care Actually Does. Findings revealed that all participants supported incorporating electronic health record palliative care triggers. Future research is needed exploring provider palliative care education approaches to promote understanding of palliative care services and to address personal and/or professional bias.

Endothelial phosphoinositide 3-kinase-ß inactivation confers protection from immune-mediated vascular injury.

Heart transplant and recipient survival are limited by immune cell-mediated injury of the graft vasculature. We examined the role of the phosphoinositide 3-kinase-ß (PI3Kß) isoform in endothelial cells (EC) during coronary vascular immune injury and repair in mice. In minor histocompatibility-antigen mismatched allogeneic heart grafts, a robust immune response was mounted to each wild-type, PI3Kß inhibitor-treated, or endothelial-selective PI3Kß knockout (ECßKO) graft transplanted to wild-type recipients. However, microvascular EC loss and progressive occlusive vasculopathy only developed in control, but not PI3Kß-inactivated hearts. We observed a delay in inflammatory cell infiltration of the ECßKO grafts, particularly in the coronary arteries. Surprisingly, this was accompanied by an impaired display of proinflammatory chemokine and adhesion molecules by the ECßKO ECs. In vitro, tumor necrosis factor α-stimulated endothelial ICAM1 and VCAM1 expression was blocked by PI3Kß inhibition or RNA interference. Selective PI3Kß inhibition also blocked tumor necrosis factor α-stimulated degradation of inhibitor of nuclear factor kappa Bα and nuclear translocation of nuclear factor kappa B p65 in EC. These data identify PI3Kß as a therapeutic target to reduce vascular inflammation and injury.

Evaluating the Potential for ABO-incompatible Islet Transplantation: Expression of ABH Antigens on Human Pancreata, Isolated Islets, and Embryonic Stem Cell-derived Islets.

BACKGROUND: ABO-incompatible transplantation has improved accessibility of kidney, heart, and liver transplantation. Pancreatic islet transplantation continues to be ABO-matched, yet ABH antigen expression within isolated human islets or novel human embryonic stem cell (hESC)-derived islets remain uncharacterized. METHODS: We evaluated ABH glycans within human pancreata, isolated islets, hESC-derived pancreatic progenitors, and the ensuing in vivo mature islets following kidney subcapsular transplantation in rats. Analyses include fluorescence immunohistochemistry and single-cell analysis using flow cytometry. RESULTS: Within the pancreas, endocrine and ductal cells do not express ABH antigens. Conversely, pancreatic acinar tissues strongly express these antigens. Acinar tissues are present in a substantial portion of cells within islet preparations obtained for clinical transplantation. The hESC-derived pancreatic progenitors and their ensuing in vivo-matured islet-like clusters do not express ABH antigens. CONCLUSIONS: Clinical pancreatic islet transplantation should remain ABO-matched because of contaminant acinar tissue within islet preparations that express ABH glycans. Alternatively, hESC-derived pancreatic progenitors and the resulting in vivo-matured hESC-derived islets do not express ABH antigens. These findings introduce the potential for ABO-incompatible cell replacement treatment and offer evidence to support scalability of hESC-derived cell therapies in type 1 diabetes.

A multi-faceted approach to sex and gender equity in solid organ transplantation: The Women in Transplantation Initiative of The Transplantation Society.

The advancement of women's careers in transplantation continues to be challenging. Academic careers in both basic and clinical disciplines in transplantation, such as surgery and management of end organ failure in medical specialties, have been underrepresented by diverse genders and ethnicities. Over the last decade, the Women in Transplantation Initiative (WIT) has solidified to becoming an internationally recognized organization with activities focused on diversity and inclusion in terms of the sexes. The WIT organization is divided into 3 pillars that address career advancement and networking (Pillar 1), scientific investigation and presentations on sex and gender in transplantation (Pillar 2) and investigating and facilitating equitable access to transplantation for women throughout the world (Pillar 3). By taking this multipronged approach of collaborating across continents, leveraging virtual platforms for information dissemination and discussion, and providing financial support for research, WIT has become a highly visible grass roots organization that aims to improve the experience of women as transplant professionals as well as transplant donors and recipients.

Imaging Tolerance Induction in Neonatal Mice: Hierarchical Interplay Between Allogeneic Adult and Neonatal Immune Cells.

BACKGROUND: In Medawar's murine neonatal tolerance model, injection of adult semiallogeneic lymphohematopoietic cells (spleen cells [SC] and bone marrow cells [BMC]) tolerizes the neonatal immune system. An eventual clinical application would require fully allogeneic (allo) cells, yet little is known about the complex in vivo/in situ interplay between those cells and the nonconditioned neonatal immune system. METHODS: To this end, labeled adult SC and BMC were injected into allogeneic neonates; interactions between donor and host cells were analyzed and modulated by systematic depletion/inactivation of specific donor and host immune effector cell types. RESULTS: Consistent with effector cell compositions, allo-SC and allo-SC/BMC each induced lethal acute graft-versus-host disease, whereas allo-BMC alone did so infrequently. CD8 T cells from SC inoculum appeared naïve, while those of BMC were more memory-like. Age-dependent, cell-type dominance defined the interplay between adult donor cells and the neonatal host immune system such that if the dominant adult effector type was removed, then the equivalent neonatal one became dominant. Depletion of donor/host peripheral T cells protected against acute graft-versus-host disease and prolonged heart allograft survival; peripheral CD8 T-cell depletion together with CD4 T cell-costimulation blockade induced more robust tolerance. CONCLUSIONS: This comprehensive study provides direct observation of the cellular interplay between allogeneic donor and host immune systems, adds to our previous work with semiallogeneic donor cells, and provides important insights for robust tolerance induction. Induction of transplant tolerance in neonates will likely require "crowd sourcing" of multiple tolerizing cell types and involve depletion of immune effector cells with costimulation blockade.

A versatile soluble siglec scaffold for sensitive and quantitative detection of glycan ligands.

Sialic acid-binding immunoglobulin-type lectins (Siglecs) are immunomodulatory receptors that are regulated by their glycan ligands. The connections between Siglecs and human disease motivate improved methods to detect Siglec ligands. Here, we describe a new versatile set of Siglec-Fc proteins for glycan ligand detection. Enhanced sensitivity and selectivity are enabled through multimerization and avoiding Fc receptors, respectively. Using these Siglec-Fc proteins, Siglec ligands are systematically profiled on healthy and cancerous cells and tissues, revealing many unique patterns. Additional features enable the production of small, homogenous Siglec fragments and development of a quantitative ligand-binding mass spectrometry assay. Using this assay, the ligand specificities of several Siglecs are clarified. For CD33 (Siglec-3), we demonstrate that it recognizes both α2-3 and α2-6 sialosides in solution and on cells, which has implications for its link to Alzheimer's disease susceptibility. These soluble Siglecs reveal the abundance of their glycan ligands on host cells as self-associated molecular patterns.

HEARTBiT: A Transcriptomic Signature for Excluding Acute Cellular Rejection in Adult Heart Allograft Patients.

BACKGROUND: Nine mRNA transcripts associated with acute cellular rejection (ACR) in previous microarray studies were ported to the clinically amenable NanoString nCounter platform. Here we report the diagnostic performance of the resulting blood test to exclude ACR in heart allograft recipients: HEARTBiT. METHODS: Blood samples for transcriptomic profiling were collected during routine post-transplantation monitoring in 8 Canadian transplant centres participating in the Biomarkers in Transplantation initiative, a large (n = 1622) prospective observational study conducted between 2009 and 2014. All adult cardiac transplant patients were invited to participate (median age = 56 [17 to 71]). The reference standard for rejection status was histopathology grading of tissue from endomyocardial biopsy (EMB). All locally graded ISHLT ≥ 2R rejection samples were selected for analysis (n = 36). ISHLT 1R (n = 38) and 0R (n = 86) samples were randomly selected to create a cohort approximately matched for site, age, sex, and days post-transplantation, with a focus on early time points (median days post-transplant = 42 [7 to 506]). RESULTS: ISHLT ≥ 2R rejection was confirmed by EMB in 18 and excluded in 92 samples in the test set. HEARTBiT achieved 47% specificity (95% confidence interval [CI], 36%-57%) given ≥ 90% sensitivity, with a corresponding area under the receiver operating characteristic curve of 0.69 (95% CI, 0.56-0.81). CONCLUSIONS: HEARTBiT's diagnostic performance compares favourably to the only currently approved minimally invasive diagnostic test to rule out ACR, AlloMap (CareDx, Brisbane, CA) and may be used to inform care decisions in the first 2 months post-transplantation, when AlloMap is not approved, and most ACR episodes occur.

Benefits and challenges with diagnosing chronic and late acute GVHD in children using the NIH consensus criteria.

Chronic graft-versus-host disease (cGVHD) and late acute graft-versus-host disease (L-aGVHD) are understudied complications of allogeneic hematopoietic stem cell transplantation in children. The National Institutes of Health Consensus Criteria (NIH-CC) were designed to improve the diagnostic accuracy of cGVHD and to better classify graft-versus-host disease (GVHD) syndromes but have not been validated in patients <18 years of age. The objectives of this prospective multi-institution study were to determine: (1) whether the NIH-CC could be used to diagnose pediatric cGVHD and whether the criteria operationalize well in a multi-institution study; (2) the frequency of cGVHD and L-aGVHD in children using the NIH-CC; and (3) the clinical features and risk factors for cGVHD and L-aGVHD using the NIH-CC. Twenty-seven transplant centers enrolled 302 patients <18 years of age before conditioning and prospectively followed them for 1 year posttransplant for development of cGVHD. Centers justified their cGVHD diagnosis according to the NIH-CC using central review and a study adjudication committee. A total of 28.2% of reported cGVHD cases was reclassified, usually as L-aGVHD, following study committee review. Similar incidence of cGVHD and L-aGVHD was found (21% and 24.7%, respectively). The most common organs involved with diagnostic or distinctive manifestations of cGVHD in children include the mouth, skin, eyes, and lungs. Importantly, the 2014 NIH-CC for bronchiolitis obliterans syndrome perform poorly in children. Past acute GVHD and peripheral blood grafts are major risk factors for cGVHD and L-aGVHD, with recipients ≥12 years of age being at risk for cGVHD. Applying the NIH-CC in pediatrics is feasible and reliable; however, further refinement of the criteria specifically for children is needed.

Equally Interchangeable? How Sex and Gender Affect Transplantation.

Organ transplantation as an option to overcome end-stage diseases is common in countries with advanced healthcare systems and is increasingly provided in emerging and developing countries. A review of the literature points to sex- and gender-based inequity in the field with differences reported at each step of the transplant process, including access to a transplantation waiting list, access to transplantation once waitlisted, as well as outcome after transplantation. In this review, we summarize the data regarding sex- and gender-based disparity in adult and pediatric kidney, liver, lung, heart, and hematopoietic stem cell transplantation and argue that there are not only biological but also psychological and socioeconomic issues that contribute to disparity in the outcome, as well as an inequitable access to transplantation for women and girls. Because the demand for organs has always exceeded the supply, the transplant community has long recognized the need to ensure equity and efficiency of the organ allocation system. In the spirit of equity and equality, the authors call for recognition of these inequities and the development of policies that have the potential to ensure that girls and women have equitable access to transplantation.

A standardized immune phenotyping and automated data analysis platform for multicenter biomarker studies.

The analysis and validation of flow cytometry-based biomarkers in clinical studies are limited by the lack of standardized protocols that are reproducible across multiple centers and suitable for use with either unfractionated blood or cryopreserved PBMCs. Here we report the development of a platform that standardizes a set of flow cytometry panels across multiple centers, with high reproducibility in blood or PBMCs from either healthy subjects or patients 100 days after hematopoietic stem cell transplantation. Inter-center comparisons of replicate samples showed low variation, with interindividual variation exceeding inter-center variation for most populations (coefficients of variability <20% and interclass correlation coefficients >0.75). Exceptions included low-abundance populations defined by markers with indistinct expression boundaries (e.g., plasmablasts, monocyte subsets) or populations defined by markers sensitive to cryopreservation, such as CD62L and CD45RA. Automated gating pipelines were developed and validated on an independent data set, revealing high Spearman's correlations (rs >0.9) with manual analyses. This workflow, which includes pre-formatted antibody cocktails, standardized protocols for acquisition, and validated automated analysis pipelines, can be readily implemented in multicenter clinical trials. This approach facilitates the collection of robust immune phenotyping data and comparison of data from independent studies.

Sex and gender considerations in transplantation research: protocol for a scoping review.

BACKGROUND: Despite the growing appreciation of the importance of sex and gender considerations in transplantation research, there is currently no framework or good practice guidelines for the appropriate handling of sex and gender issues in human allotransplantation research. METHODS: We will conduct a scoping review to synthesize the evidence on how matters of sex and gender have been handled in human allotransplantation research. We will survey the literature discussing sex and gender in relation to transplantation, including adult and pediatric patients, hematopoietic and solid organ transplant recipients as well as organ donors. We will search MEDLINE and Embase for literature discussing sex and gender in relation to transplantation. Two reviewers will independently evaluate the eligibility of all identified titles and abstracts for inclusion in the full text review, as well as data extraction. Descriptive data and information on how sex and gender have been considered in human transplantation research will be reported. DISCUSSION: This scoping review will be an important stepping stone towards the development of good practice guidelines on study design and analysis considerations when handling sex and gender issues in human transplantation research. This scoping review can also help identify methodological issues that restrict the translation of transplantation research findings into clinical practice related to underestimation of sex/gender differences. This review will ultimately identify major gaps, inform donor-recipient selection, guide personalized interventions, and prioritize research recommendations in human transplantation research.

Glutaraldehyde Treatment of Allografts and Aortic Outcomes Post-Norwood: Challenging Surgical Decision.

BACKGROUND: Glutaraldehyde (GA) treatment of allografts used for arch reconstruction prevents the immunologic sensitization that occurs with untreated allografts, but its use may cause tissue changes that predispose to recurrent obstruction. The objective was to determine whether GA treatment of allografts used in Norwood procedures increases the risk of recurrent aortic obstruction. METHODS: All infants who underwent a Norwood procedure between 2000 and 2015 were included. Cryopreserved pulmonary allografts were used for all arch reconstructions; starting in 2005 all were treated with GA before use. Complete follow-up was obtained, including survival, transplantation, and all repeat procedures. Competing risks analyses were used to assess for differences in aortic reintervention over time. RESULTS: Two hundred six infants (132 male) were included. There were 60 deaths and 14 transplantations; 5-year transplantation-free survival was 71.9%. GA treatment of patches (n = 142, 68.9%) was not predictive of death (hazard ratio [HR] 1.38, 95% confidence interval [CI]: 0.61 to 3.08). Fifty-five patients had at least one aortic reintervention and 31 patients (15.0%) required surgical aortic reintervention. At 1-year, freedom from all aortic reintervention was similar between patients with and without treated patches, but freedom from surgical aortic reintervention was lower in the treated group (87.6% versus 95.3%, p = 0.0256). GA treatment was not associated with the combined end point of catheter-based or surgical reintervention but was associated with specific need for surgical reintervention (HR 4.05, 95% CI: 1.19 to 13.77). CONCLUSIONS: GA treatment is associated with increased late surgical aortic reintervention. The advantages of decreased sensitization with GA treatment need to be balanced against the risk of aortic reobstruction.

Transdisciplinary tour-de-force: The Canadian National Transplant Research Program.

The Canadian National Transplant Research Program, launched in 2013 with funding from the Canadian Institutes for Health Research and partners, bridges research in the fields of solid organ transplant, hematopoietic cell transplant, and organ donation. We describe the philosophy, structure, accomplishments, and challenges faced by the Canadian National Transplant Research Program to expand on facilitators and overcome roadblocks to successfully developing a transdisciplinary national research structure.

Myocyte growth, repair, and oxidative stress following pediatric heart transplantation.

Cardiac remodeling is associated with plasma biomarkers of fibrinogenesis, inflammation, and oxidative stress, and upregulation of mitogenic, pro-fibrotic, and apoptotic signaling pathways. Our primary objective was to evaluate biomarker and subcellular myocardial changes in pediatric heart transplant recipients. Fifty-two-week prospective, randomized (tacrolimus, Tac, vs. cyclosporine, CsA), open-label, parallel group study. Serial myocardial biopsies were probed for mitogenic and pro-inflammatory proteins. Plasma biomarkers of oxidative stress (F2α isoprostanes, nitrotyrosine), and inflammation and oxidation (hsCRP and cystatin-C) were measured. Nine of 11 randomized patients completed the study (four Tac, five CsA). Mean levels of F2α isoprostanes, hsCRP, and cystatin-C were maximal at Week 2. Peak activation of all MAP kinases in myocardial tissue was maximal at Week 10; no association was seen with rejection. Cardiac Bax/Bcl-2 levels (index of apoptosis) correlated negatively with F2α isoprostanes at Week 2 (r = -0.88) and with hsCRP at Week 52 (r = -0.67). At Week 52, hsCRP levels correlated positively with molecular indices of cardiac cell growth. We found evidence of systemic and myocardial oxidative damage and inflammation early posttransplant, which may be related to the remodeling process. Further study is needed to better understand the cardiac and systemic repair processes following pediatric heart transplantation.

Mechanical ventricular assist device as a bridge to recovery post-ABO-incompatible heart transplantation for failed Fontan circulation.

A girl received an ABO-incompatible heart transplantation (ABOiHTx) at the age of 3.5 years for failed univentricular palliation with protein-losing enteropathy (PLE). She was born with a hypoplastic left heart syndrome and underwent multistage palliation to a Fontan circulation at 2½ years of age. After the Fontan surgery, she developed PLE, necessitating a Fontan revision, followed by a Fontan takedown and eventually HTx, which was performed with a blood group B heart into an O recipient. Right ventricular (RV) failure secondary to increased pulmonary vascular resistance (PVR) evolved immediately after HTx. A temporary right ventricular assist device (RVAD) was implanted and later switched to a pneumatic pulsatile RVAD. With the adaption of PVR on the RVAD, the PLE resolved and the RVAD was explanted. In the following 12 months, she developed multiple relapses of PLE which eventually resolved after exchange of the calcineurin inhibitor.

Failure of neonatal B-cell tolerance induction by ABO-incompatible kidney grafts in piglets.

BACKGROUND: ABO-incompatible (ABOi) infant heart transplantation results in B-cell tolerance to graft A/B antigens, confirming human susceptibility to acquired immunologic or "neonatal" tolerance as described originally in murine models. Starting with this clinical observation, we sought to model neonatal ABOi organ transplantation to allow mechanistic studies of tolerance. METHODS: Plasma anti-A/B antibodies were measured over time in piglets to establish developmental antibody kinetics. Blood group O piglets received kidney allografts from group A (AO-incompatible) or group O (AO-compatible) donors under cyclosporine immunosuppression. Anti-A antibodies were measured serially after transplantation; A/H antigen expression and allograft rejection were assessed in graft biopsies. RESULTS: Anti-A antibodies developed in naïve piglets in a kinetic pattern analogous to human infants; anti-B remained low. After transplantation, anti-A antibodies developed similarly in AO-incompatible and AO-compatible groups and were not suppressed by cyclosporine. A/H antigen expression was persistent in all graft biopsies; however, A/H antigens were not detected in vascular endothelium. Cellular and antibody-mediated rejection was absent or minimal in early and late biopsies in both groups, with one exception. CONCLUSIONS: Naturally delayed isohemagglutinin production in piglets is analogous to the developmental kinetics in human infants. However, in contrast to deficient anti-A antibody production as seen long-term after "A-into-O" infant heart transplant recipients, normal anti-A antibody production after "A-into-O" piglet kidney transplantation indicates that tolerance did not develop despite graft A antigen persistence. These findings suggest that the impact on the host immune system of exposure to nonself ABH antigens during early life in human heart versus porcine kidney grafts may depend on expression in vascular endothelium.

The profile of the systemic inflammatory response in children undergoing ventricular assist device support.

OBJECTIVES: Serum C-reactive protein (CRP) has been used as a systemic inflammatory response (SIR) marker in the critical ill, including children after cardiopulmonary bypass surgery. Ventricular assist devices (VAD) have been increasingly used as a bridge support to heart transplantation in children. We aimed to examine the profiles of CRP in children receiving VAD support. METHODS: Charts of 13 children receiving Berlin Heart EXCOR(®) from 2005 to 2009 were reviewed. The data obtained prior to and during VAD support included: CRP, white blood cells, inotropes and steroid use, VAD mode and duration of VAD support. Ten patients received left VAD (LVAD) and 3 biventricular VAD (BiVAD). RESULTS: The median duration of VAD support was 59 days (ranged 3-678 days). Pre-VAD CRP was 35 ± 51 mg/l and increased to 109 ± 59 mg/l on days 1-3 after the VAD implantation (P = 0.01), then gradually decreased to 28 ± 28 mg/l by 4 months and normalized by 5 months (P < 0.0001). CRP was higher in BiVAD than in LVAD patients throughout the study period (P = 0.003). CRP positively correlated with the doses of the epinephrine and norepinephrine and the monocyte counts, and negatively correlated with the lymphocyte count. The lymphocyte count was 2.5 ± 0.4 x 10(9)/l prior to implantation, and decreased to 2.1 ± 1.3 x 10(9)/l on days 1-3 (P = 0.5) and then to 0.6 ± 0.1 x 10(9)/l by 6 months (P = 0.08). It tended to be lower in BiVAD patients (P = 0.06). CONCLUSIONS: SIR exists in children prior to VAD support. VAD implantation is associated with a significant and prolonged increase in CRP and a decrease in lymphocyte count, indicating a suppressed immune function, being more pronounced in BiVAD patients.

T-cell-based immunosuppressive therapy inhibits the development of natural antibodies in infant baboons.

BACKGROUND: We set out to determine whether B-cell tolerance to A/B-incompatible alloantigens and pig xenoantigens could be achieved in infant baboons. METHODS: Artery patch grafts were implanted in the abdominal aorta in 3-month-old baboons using A/B-incompatible (AB-I) allografts or wild-type pig xenografts (pig). Group 1 (Gp1) (controls, n=6) received no immunosuppressive therapy (IS) and no graft. Gp2 (n=2) received an AB-I or pig graft but no IS. Gp3 received AB-I grafts+IS (Gp3A: n=2) or pig grafts+IS (Gp3B: n=2). IS consisted of ATG, anti-CD154mAb, and mycophenolate mofetil until age 8 to 12 months. Gp4 (n=2) received IS only but no graft. RESULTS: In Gp1, anti-A/B and cytotoxic anti-pig immunoglobulin-M increased steadily during the first year. Gp2 became sensitized to donor-specific AB-I or pig antigens within 2 weeks. Gp3 and Gp4 infants that received anti-CD154mAb made no or minimal anti-A/B and anti-pig antibodies while receiving IS. DISCUSSION: The production of natural anti-A/B and anti-pig antibodies was inhibited by IS with anti-CD154mAb, even in the absence of an allograft or xenograft, suggesting that natural antibodies may not be entirely T-cell independent. These data are in contrast to clinical experience with AB-I allotransplantation in infants, who cease producing only donor-specific antibodies.

Mechanisms of cytosolic targeting of matrix metalloproteinase-2.

Matrix metalloproteinase-2 (MMP-2) is best understood for its biological actions outside the cell. However, MMP-2 also localizes to intracellular compartments and the cytosol where it has several substrates, including troponin I (TnI). Despite a growing list of cytosolic substrates, we currently do not know the mechanism(s) that give rise to the equilibrium between intracellular and secreted MMP-2 moieties. Therefore, we explored how cells achieve the unique distribution of this protease. Our data show that endogenous MMP-2 targets inefficiently to the endoplasmic reticulum (ER) and shows significant amounts in the cytosol. Transfection of canonical MMP-2 essentially reproduces this targeting pattern, suggesting it is the quality of the MMP-2 signal sequence that predominantly determines MMP-2 targeting. However, we also found that human cardiomyocytes express an MMP-2 splice variant which entirely lacks the signal sequence. Like the fraction of ER-excluded, full-length MMP-2, this variant MMP-2 is restricted to the cytosol and specifically enhances TnI cleavage upon hypoxia-reoxygenation injury in cardiomyocytes. Together, our findings describe for the first time a set of mechanisms that cells utilize to equilibrate MMP-2 both in the extracellular milieu and intracellular, cytosolic locations. Our results also suggest approaches to specifically investigate the overlooked intracellular biology of MMP-2.