Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model.

ObjectiveThis study aimed to examine acellular extracellular matrix based hydrogels as potential therapies for treating peripheral artery disease (PAD). We tested the efficacy of using a tissue specific injectable hydrogel, derived from decellularized porcine skeletal muscle (SKM), compared to a new human umbilical cord derived matrix (hUC) hydrogel, which could have greater potential for tissue regeneration because of its young tissue source age.BackgroundThe prevalence of PAD is increasing and can lead to critical limb ischemia (CLI) with potential limb amputation. Currently there are no therapies for PAD that effectively treat all of the underlying pathologies, including reduced tissue perfusion and muscle atrophy.MethodsIn a rodent hindlimb ischemia model both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis (LASCA) to 35 days post-injection. Histology and immunohistochemistry were used to assess neovascularization and muscle health. Whole transcriptome analysis was further conducted on SKM injected animals on 3 and 10 days post-injection.ResultsSignificant improvements in hindlimb tissue perfusion and perfusion kinetics were observed with both biomaterials. End point histology indicated this was a result of arteriogenesis, rather than angiogenesis, and that the materials were biocompatible. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue specific, SKM hydrogel more closely matched healthy tissue morphology. Short term histology also indicated arteriogenesis rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development.ConclusionThese results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Human versus porcine tissue sourcing for an injectable myocardial matrix hydrogel

Heart failure (HF) after myocardial infarction (MI) is a leading cause of death in the western world with a critical need for new therapies. A previously developed injectable hydrogel derived from porcine myocardial matrix (PMM) has had successful results in both small and large animal MI models. In this study, we sought to evaluate the impact of tissue source on this biomaterial, specifically comparing porcine and human myocardium sources. We first developed an analogous hydrogel derived from human myocardial matrix (HMM). The biochemical and physical properties of the PMM and HMM hydrogels were then characterized, including residual dsDNA, protein content, sulfated glycosaminoglycan (sGAG) content, complex viscosity, storage and loss moduli, and nano-scale topography. Biochemical activity was investigated with in vitro studies for the proliferation of vascular cells and differentiation of human cardiomyocyte progenitor cells (hCMPCs). Next, in vivo gelation and material spread were confirmed for both PMM and HMM after intramyocardial injection. After extensive comparison, the matrices were found to be similar, yet did show some differences. Because of the rarity of collecting healthy human hearts, the increased difficulty in processing the human tissue, shifts in extracellular matrix (ECM) composition due to aging, and significant patient-to-patient variability, these studies suggest that the HMM is not a viable option as a scalable product for the clinic; however, the HMM has potential as a tool for in vitro cell culture

Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model.

ObjectiveThis study aimed to examine acellular extracellular matrix based hydrogels as potential therapies for treating peripheral artery disease (PAD). We tested the efficacy of using a tissue specific injectable hydrogel, derived from decellularized porcine skeletal muscle (SKM), compared to a new human umbilical cord derived matrix (hUC) hydrogel, which could have greater potential for tissue regeneration because of its young tissue source age.BackgroundThe prevalence of PAD is increasing and can lead to critical limb ischemia (CLI) with potential limb amputation. Currently there are no therapies for PAD that effectively treat all of the underlying pathologies, including reduced tissue perfusion and muscle atrophy.MethodsIn a rodent hindlimb ischemia model both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis (LASCA) to 35 days post-injection. Histology and immunohistochemistry were used to assess neovascularization and muscle health. Whole transcriptome analysis was further conducted on SKM injected animals on 3 and 10 days post-injection.ResultsSignificant improvements in hindlimb tissue perfusion and perfusion kinetics were observed with both biomaterials. End point histology indicated this was a result of arteriogenesis, rather than angiogenesis, and that the materials were biocompatible. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue specific, SKM hydrogel more closely matched healthy tissue morphology. Short term histology also indicated arteriogenesis rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development.ConclusionThese results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment

Engineering an Injectable Muscle-Specific Microenvironment for Improved Cell Delivery Using a Nanofibrous Extracellular Matrix Hydrogel

Injection of skeletal muscle progenitors has the potential to be a minimally invasive treatment for a number of diseases that negatively affect vasculature and skeletal muscle, including peripheral artery disease. However, success with this approach has been limited because of poor transplant cell survival. This is primarily attributed to cell death due to extensional flow through the needle, the harsh ischemic environment of the host tissue, a deleterious immune cell response, and a lack of biophysical cues supporting exogenous cell viability. We show that engineering a muscle-specific microenvironment, using a nanofibrous decellularized skeletal muscle extracellular matrix hydrogel and skeletal muscle fibroblasts, improves myoblast viability and maturation <i>in vitro</i>. <i>In vivo</i>, this translates to improved cell survival and engraftment and increased perfusion as a result of increased vascularization. Our results indicate that a combinatorial delivery system, which more fully recapitulates the tissue microenvironment, can improve cell delivery to skeletal muscle

Preventing post-surgical cardiac adhesions with a catechol-functionalized oxime hydrogel

Postsurgical adhesions are a problem during routine cardiothoracic procedures. Here, the authors report on a catechol functionalised hydrogel as an anti-adhesion material with improved retention on the heart which is biocompatible and biodegradable with minimal swelling, demonstrating application in vivo

Preventing post-surgical cardiac adhesions with a catechol-functionalized oxime hydrogel

Post-surgical cardiac adhesions represent a significant problem during routine cardiothoracic procedures. This fibrous tissue can impair heart function and inhibit surgical access in reoperation procedures. Here, we propose a hydrogel barrier composed of oxime crosslinked poly(ethylene glycol) (PEG) with the inclusion of a catechol (Cat) group to improve retention on the heart for pericardial adhesion prevention. This three component system is comprised of aldehyde (Ald), aminooxy (AO), and Cat functionalized PEG mixed to form the final gel (Ald-AO-Cat). Ald-AO-Cat has favorable mechanical properties, degradation kinetics, and minimal swelling, as well as superior tissue retention compared to an initial Ald-AO gel formulation. We show that the material is cytocompatible, resists cell adhesion, and led to a reduction in the severity of adhesions in an in vivo rat model. We further show feasibility in a pilot porcine study. The Ald-AO-Cat hydrogel barrier may therefore serve as a promising solution for preventing post-surgical cardiac adhesions

Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model

Although surgical and endovascular revascularization can be performed in peripheral arterial disease (PAD), 40% of patients with critical limb ischemia do not have a revascularization option. This study examines the efficacy and mechanisms of action of acellular extracellular matrix-based hydrogels as a potential novel therapy for treating PAD. We tested the efficacy of using a tissue-specific injectable hydrogel derived from decellularized porcine skeletal muscle (SKM) and compared this to a new human umbilical cord-derived matrix (hUC) hydrogel, which could have greater potential for tissue regeneration because of the younger age of the tissue source. In a rodent hindlimb ischemia model, both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis to 35 days post-injection. There were significant improvements in hindlimb tissue perfusion and perfusion kinetics with both biomaterials. Histologic analysis indicated that the injected hydrogels were biocompatible, and resulted in arteriogenesis, rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue-specific SKM hydrogel more closely matched healthy tissue morphology. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development. These results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment