Tissue-engineered pro-angiogenic fibroblast scaffold improves myocardial perfusion and function and limits ventricular remodeling after infarction

Shen'ge Formula Protects Cardiac Function in Rats with Pressure Overload-Induced Heart Failure

Background

In China, Shen'ge formula (SGF), a Traditional Chinese Medicine blend crafted from ginseng and gecko, holds a revered place in the treatment of cardiovascular diseases. However, despite its prevalent use, the precise cardioprotective mechanisms of SGF remain largely uncharted. This study aims to fill this gap by delving deeper into SGF's therapeutic potential and underlying action mechanism, thus giving its traditional use a solid scientific grounding.

Methods

In this study, rats were subjected to abdominal aortic constriction (AAC) to generate pressure overload. Following AAC, we administered SGF and bisoprolol intragastrically at specified doses for two distinct durations: 8 and 24 weeks. The cardiac function post-treatment was thoroughly analyzed using echocardiography and histological examinations, offering insights into SGF's influence on vital cardiovascular metrics, and signaling pathways central to cardiac health.

Results

SGF exhibited promising results, significantly enhanced cardiac functions over both 8 and 24-week periods, evidenced by improved ejection fraction and fractional shortening while moderating left ventricular parameters. Noteworthy was SGF's role in the significant mitigation of myocardial hypertrophy and in fostering the expression of vital proteins essential for heart health by the 24-week mark. This intervention markedly altered the dynamics of the Akt/HIF-1α/p53 pathway, inhibiting detrimental processes while promoting protective mechanisms.

Conclusion

Our research casts SGF in a promising light as a cardioprotective agent in heart failure conditions induced by pressure overload in rats. Central to this protective shield is the modulation of the Akt/HIF-1α/p53 pathway, pointing to a therapeutic trajectory that leverages HIF-1α promotion and p53 nuclear transport inhibition.

Adult spiny mice (Acomys) exhibit endogenous cardiac recovery in response to myocardial infarction

Complex tissue regeneration is extremely rare among adult mammals. An exception, however, is the superior tissue healing of multiple organs in spiny mice (Acomys). While Acomys species exhibit the remarkable ability to heal complex tissue with minimal scarring, little is known about their cardiac structure and response to cardiac injury. In this study, we first examined baseline Acomys cardiac anatomy and function in comparison with commonly used inbred and outbred laboratory Mus strains (C57BL6 and CFW). While our results demonstrated comparable cardiac anatomy and function between Acomys and Mus, Acomys exhibited a higher percentage of cardiomyocytes displaying distinct characteristics. In response to myocardial infarction, all animals experienced a comparable level of initial cardiac damage. However, Acomys demonstrated superior ischemic tolerance and cytoprotection in response to injury as evidenced by cardiac functional stabilization, higher survival rate, and smaller scar size 50 days after injury compared to the inbred and outbred mouse strains. This phenomenon correlated with enhanced endothelial cell proliferation, increased angiogenesis, and medium vessel maturation in the peri-infarct and infarct regions. Overall, these findings demonstrate augmented myocardial preservation in spiny mice post-MI and establish Acomys as a new adult mammalian model for cardiac research.

CD73+ extracellular vesicles inhibit angiogenesis through adenosine A2B receptor signalling

Pathological angiogenesis is a hallmark of several conditions including eye diseases, inflammatory diseases, and cancer. Stromal cells play a crucial role in regulating angiogenesis through the release of soluble factors or direct contact with endothelial cells. Here, we analysed the properties of the extracellular vesicles (EVs) released by bone marrow mesenchymal stromal cells (MSCs) and explored the possibility of using them to therapeutically target angiogenesis. We demonstrated that in response to pro-inflammatory cytokines, MSCs produce EVs that are enriched in TIMP-1, CD39 and CD73 and inhibit angiogenesis targeting both extracellular matrix remodelling and endothelial cell migration. We identified a novel anti-angiogenic mechanism based on adenosine production, triggering of A2B adenosine receptors, and induction of NOX2-dependent oxidative stress within endothelial cells. Finally, in pilot experiments, we exploited the anti-angiogenic EVs to inhibit tumour progression in vivo. Our results identify novel pathways involved in the crosstalk between endothelial and stromal cell and suggest new therapeutic strategies to target pathological angiogenesis.

Photobiomodulation plus Adipose-derived Stem Cells Improve Healing of Ischemic Infected Wounds in Type 2 Diabetic Rats

In this study, we sought to investigate the impact of photobiomodulation and adipose-derived stem cells (ADS), alone and in combination, on the maturation step of wound healing in an ischemic infected delayed healing wound model in rats with type 2 diabetes mellitus (DM2). We randomly divided 24 adult male rats into 4 groups (n = 6 per group). DM2 plus an ischemic delayed healing wound were induced in all rats. The wounds were infected with methicillin-resistant Staphylococcus aureus. Group 1 was the control (placebo) group. Group 2 received only photobiomodulation (890 nm, 80 Hz, 0.324 J/cm², and 0.001 W/cm²). Group 3 received only the allograft ADS. Group 4 received allograft ADS followed by photobiomodulation. On days 0, 4, 8, 12, and 16, we performed microbiological examination (colony forming units, [CFU]), wound area measurement, wound closure rate, wound strength, and histological and stereological examinations. The results indicated that at day 16, there was significantly decreased CFU (Analysis of variance, p = 0.001) in the photobiomodulation + ADS (0.0 ± 0.0), ADS (1350 ± 212), and photobiomodulation (0.0 ± 0.0) groups compared with the control group (27250 ± 1284). There was significantly decreased wound area (Analysis of variance, p = 0.000) in the photobiomodulation + ADS (7.4 ± 1.4 mm²), ADS (11 ± 2.2 mm²), and photobiomodulation (11.4 ± 1.4 mm²) groups compared with the control group (25.2 ± 1.7). There was a significantly increased tensiometeric property (stress maximal load, Analysis of variance, p = 0.000) in the photobiomodulation + ADS (0.99 ± 0.06 N/cm²), ADS (0.51 ± 0.12 N/cm²), and photobiomodulation (0.35 ± 0.15 N/cm²) groups compared with the control group (0.18 ± 0.04). There was a significantly modulated inflammatory response in (Analysis of variance, p = 0.049) in the photobiomodulation + ADS (337 ± 96), ADS (1175 ± 640), and photobiomodulation (69 ± 54) treatments compared to control group (7321 ± 4099). Photobiomodulation + ADS gave significantly better improvements in CFU, wound area, and wound strength compared to photobiomodulation or ADS alone. Photobiomodulation, ADS, and their combination significantly hastened healing in ischemic methicillin-resistant Staphylococcus aureus infected delayed healing wounds in rats with DM2. Combined application of photobiomodulation plus ADS demonstrated an additive effect.

Decellularized extracellular matrix microparticles seeded with bone marrow mesenchymal stromal cells for the treatment of full-thickness cutaneous wounds

Extracellular matrix materials mechanically dissociated into submillimeter particles have a larger surface area than sheet materials and enhanced cellular attachment. Decellularized porcine mesothelial extracellular matrix microparticles were seeded with bone marrow-derived mesenchymal stromal cells and cultured in a rotating bioreactor. The mesenchymal stromal cells attached and grew to confluency on the microparticles. The cell-seeded microparticles were then encapsulated in varying concentrations of fibrin glue, and the cells migrated rapidly off the microparticles. The combination of microparticles and mesenchymal stromal cells was then applied to a splinted full-thickness cutaneous in vivo wound model. There was evidence of increased cell infiltration and collagen deposition in mesenchymal stromal cells-treated wounds. Cell-seeded microparticles have potential as a cell delivery and paracrine therapy in impaired healing environments.

Myocardial regenerative therapy using a scaffold-free skeletal-muscle-derived cell sheet in patients with dilated cardiomyopathy even under a left ventricular assist device: a safety and feasibility study

BACKGROUND AND PURPOSE

Despite promising experimental results, clinically, intramyocardial myoblast injection failed to reverse remodeling and it induced arrhythmogenicity. In contrast, scaffold-free skeletal muscle-derived cell (SC) sheets attenuated cardiac dysfunction and arrhythmogenicity via paracrine effects. We report the first clinical trial of SC sheet implantation (SCSI) conducted in four patients with dilated cardiomyopathy (DCM) supported by a left ventricular assist device (LVAD).

METHODS

SC sheets were made from muscle fibers and multi-layered SC sheets were applied to the left ventricular (LV) anterolateral surface via left thoracotomy.

RESULTS

There were no major cardiac adverse events. Ventricular arrhythmia decreased in all except one patient, in whom global LV function did not improve. The LV volume decreased and LV ejection fraction improved in all except the same patient. Systolic wall thickening, reflecting regional wall motion, improved in the sheet-implanted areas, and vessels in the LV apex increased in all patients, suggesting angiogenesis. The LVAD was successfully removed in two patients.

CONCLUSIONS

SCSI induced reverse remodeling and angiogenesis, and improved LV function, allowing LVAD removal in two patients, although functional recovery failed to improve in the one non-responder, even with angiogenesis. SCSI is a promising regenerative therapy for DCM patients responsive to this strategy, even with LVAD assistance.

Decellularized extracellular matrix microparticles as a vehicle for cellular delivery in a model of anastomosis healing

Extracellular matrix (ECM) materials from animal and human sources have become important materials for soft tissue repair. Microparticles of ECM materials have increased surface area and exposed binding sites compared to sheet materials. Decellularized porcine peritoneum was mechanically dissociated into 200 µm microparticles, seeded with fibroblasts and cultured in a low gravity rotating bioreactor. The cells avidly attached and maintained excellent viability on the microparticles. When the seeded microparticles were placed in a collagen gel, the cells quickly migrated off the microparticles and through the gel. Cells from seeded microparticles migrated to and across an in vitro anastomosis model, increasing the tensile strength of the model. Cell seeded microparticles of ECM material have potential for paracrine and cellular delivery therapies when delivered in a gel carrier. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1728-1735, 2016.

Design of nanomaterial based systems for novel vaccine development

With lower cell toxicity and higher specificity, novel vaccines have been greatly developed and applied to emerging infectious and chronic diseases. However, due to problems associated with low immunogenicity and complicated processing steps, the development of novel vaccines has been limited. With the rapid development of bio-technologies and material sciences, nanomaterials are playing essential roles in novel vaccine design. Incorporation of nanomaterials is expected to improve delivery efficiency, to increase immunogenicity, and to reduce the administration dosage. The purpose of this review is to discuss the employment of nanomaterials, including polymeric nanoparticles, liposomes, virus-like particles, peptide amphiphiles micelles, peptide nanofibers and microneedle arrays, in vaccine design. Compared to traditional methods, vaccines made from nanomaterials display many appealing benefits, including precise stimulation of immune responses, effective targeting to certain tissue or cells, and desirable biocompatibility. Current research suggests that nanomaterials may improve our approach to the design and delivery of novel vaccines.

Neonatal Human Dermal Fibroblasts Immobilized in RGD–Alginate Induce Angiogenesis

Promoting angiogenesis in a damaged tissue is a major challenge for tissue regeneration. Recent findings in tissue engineering suggest that fibroblasts (FBs) play an important role in orchestrating the angiogenic process. Fibroblasts maintain the structural integrity of connective tissue by continuously secreting growth factors and extracellular matrix precursors, which are essential for endothelial cell (EC) adhesion and spreading, thus playing a crucial role in angiogenesis. We hypothesized that FBs immobilized in alginate gels grafted with the RGD peptidic sequence could influence the recruitment of ECs to improve vascularization. In this work, the modulation of immobilized human FBs within the 3D synthetic extracellular matrix was assessed. Experiments using cocultures of ECs and FBs in indirect contact as well as angiogenic assays were performed to assess the influence of FBs immobilized in RGD–alginate in ECs' viability, stabilization, sprouting, and assembly into capillary-like structures. This study demonstrates the ability of FBs immobilized within RGD–alginate microspheres to modulate and support capillary-like structures' assembly. These findings indicate that the microenvironment created by these stromal cells in the scaffold modulates capillary morphogenesis, thus stimulating angiogenesis in situ and can potentially be used in regenerative medicine in clinical scenarios where vascularization is essential.

An electrically coupled tissue-engineered cardiomyocyte scaffold improves cardiac function in rats with chronic heart failure

BACKGROUND

Varying strategies are currently being evaluated to develop tissue-engineered constructs for the treatment of ischemic heart disease. This study examines an angiogenic and biodegradable cardiac construct seeded with neonatal cardiomyocytes for the treatment of chronic heart failure (CHF).

METHODS

We evaluated a neonatal cardiomyocyte (NCM)-seeded 3-dimensional fibroblast construct (3DFC) in vitro for the presence of functional gap junctions and the potential of the NCM-3DFC to restore left ventricular (LV) function in an in vivo rat model of CHF at 3 weeks after permanent left coronary artery ligation.

RESULTS

The NCM-3DFC demonstrated extensive cell-to-cell connectivity after dye injection. At 5 days in culture, the patch contracted spontaneously in a rhythmic and directional fashion at 43 ± 3 beats/min, with a mean displacement of 1.3 ± 0.3 mm and contraction velocity of 0.8 ± 0.2 mm/sec. The seeded patch could be electrically paced at nearly physiologic rates (270 ± 30 beats/min) while maintaining coordinated, directional contractions. Three weeks after implantation, the NCM-3DFC improved LV function by increasing (p < 0.05) ejection fraction 26%, cardiac index 33%, dP/dt(+) 25%, dP/dt(-) 23%, and peak developed pressure 30%, while decreasing (p < 0.05) LV end diastolic pressure 38% and the time constant of relaxation (Tau) 16%. At 18 weeks after implantation, the NCM-3DFC improved LV function by increasing (p < 0.05) ejection fraction 54%, mean arterial pressure 20%, dP/dt(+) 16%, dP/dt(-) 34%, and peak developed pressure 39%.

CONCLUSIONS

This study demonstrates that a multicellular, electromechanically organized cardiomyocyte scaffold, constructed in vitro by seeding NCM onto 3DFC, can improve LV function long-term when implanted in rats with CHF.

Therapeutic application of nanotechnology in cardiovascular and pulmonary regeneration

Recently, a wide range of nanotechnologies has been approached for material modification by realizing the fact that the extracellular matrix (ECM) consists of nanoscale components and exhibits nanoscale architectures. Moreover, cell-cell and cell- ECM interactions actively occur on the nanoscale and ultimately play large roles in determining cell fate in tissue engineering. Nanomaterials have provided the potential to preferentially control the behavior and differentiation of cells. The present paper reviews the need for nanotechnology in regenerative medicine and the role of nanotechnology in repairing, restoring, and regenerating damaged body parts, such as blood vessels, lungs, and the heart.

Calcium-alginate hydrogel-encapsulated fibroblasts provide sustained release of vascular endothelial growth factor

Vascularization of engineered or damaged tissues is essential to maintain cell viability and proper tissue function. Revascularization of the left ventricle (LV) of the heart after myocardial infarction is particularly important, since hypoxia can give rise to chronic heart failure due to inappropriate remodeling of the LV after death of cardiomyocytes (CMs). Fibroblasts can express vascular endothelial growth factor (VEGF), which plays a major role in angiogenesis and also acts as a chemoattractant and survival factor for CMs and cardiac progenitors. In this in vitro model study, mouse NIH 3T3 fibroblasts encapsulated in 2% w/v Ca-alginate were shown to remain viable for 150 days. Semiquantitative reverse transcription-polymerase chain reaction and immunohistochemistry demonstrated that over 21 days of encapsulation, fibroblasts continued to express VEGF, while enzyme-linked immunosorbent assay showed that there was sustained release of VEGF from the Ca-alginate during this period. The scaffold degraded gradually over the 21 days, without reduction in volume. Cells released from the Ca-alginate at 7 and 21 days as a result of scaffold degradation were shown to retain viability, to adhere to fibronectin in a normal manner, and continue to express VEGF, demonstrating their potential to further contribute to maintenance of cardiac function after scaffold degradation. This model in vitro study therefore demonstrates that fibroblasts encapsulated in Ca-alginate provide sustained release of VEGF.

Dermagraft: Use in the Treatment of Chronic Wounds

PROBLEM

Lower limb ulceration is a common problem in clinical practice. A variety of metabolic and physical causes can lead to a diversity of chronic ulcer types, including diabetic foot ulcers (DFUs) and venous leg ulcers (VLUs).

SOLUTION

A wide variety of technologies have been developed to treat chronic wounds, with varying levels of success. Depending upon the type and severity of the wound being treated, treatments may include systemic or local antibiotic therapy, application of fillers such as collagen sponges, use of negative wound pressure, hyperbaric oxygen therapy, application of select growth factors, advanced wound dressings, and more recently, the use of cell-based tissue-engineered products.

NEW TECHNOLOGY

Dermagraft^® is a sterile, cryopreserved, human fibroblast-derived dermal substitute generated by the culture of neonatal dermal fibroblasts onto a bioabsorbable polyglactin mesh scaffold. During the product-manufacturing process, the human fibroblasts proliferate to fill the interstices of this scaffold and secrete collagen, other extracellular matrix proteins, growth factors, and cytokines, creating a three-dimensional human tissue containing metabolically active living cells.

INDICATIONS FOR USE

Dermagraft has been approved for marketing in the United States for the treatment of DFUs. In addition, the product is in active development for the treatment of VLUs and has been clinically used in a variety of other indications to stimulate wound healing.

CAUTION

When treating DFUs, Dermagraft should be used in conjunction with standard wound care regimens and in patients who have adequate blood supply to the involved foot.

Myocardial tissue elastic properties determined by atomic force microscopy after stromal cell-derived factor 1α angiogenic therapy for acute myocardial infarction in a murine model

OBJECTIVES

Ventricular remodeling after myocardial infarction begins with massive extracellular matrix deposition and resultant fibrosis. This loss of functional tissue and stiffening of myocardial elastic and contractile elements starts the vicious cycle of mechanical inefficiency, adverse remodeling, and eventual heart failure. We hypothesized that stromal cell-derived factor 1α (SDF-1α) therapy to microrevascularize ischemic myocardium would rescue salvageable peri-infarct tissue and subsequently improve myocardial elasticity.

METHODS

Immediately after left anterior descending coronary artery ligation, mice were randomly assigned to receive peri-infarct injection of either saline solution or SDF-1α. After 6 weeks, animals were killed and samples were taken from the peri-infarct border zone and the infarct scar, as well as from the left ventricle of noninfarcted control mice. Determination of tissues' elastic moduli was carried out by mechanical testing in an atomic force microscope.

RESULTS

SDF-1α-treated peri-infarct tissue most closely approximated the elasticity of normal ventricle and was significantly more elastic than saline-treated peri-infarct myocardium (109 ± 22.9 kPa vs 295 ± 42.3 kPa; P < .0001). Myocardial scar, the strength of which depends on matrix deposition from vasculature at the peri-infarct edge, was stiffer in SDF-1α-treated animals than in controls (804 ± 102.2 kPa vs 144 ± 27.5 kPa; P < .0001).

CONCLUSIONS

Direct quantification of myocardial elastic properties demonstrates the ability of SDF-1α to re-engineer evolving myocardial infarct and peri-infarct tissues. By increasing elasticity of the ischemic and dysfunctional peri-infarct border zone and bolstering the weak, aneurysm-prone scar, SDF-1α therapy may confer a mechanical advantage to resist adverse remodeling after infarction.

Nanoparticles targeting the infarcted heart

We report a nanoparticulate system capable of targeting the heart after myocardial infarction (MI). Targeting is based on overexpression of angiotensin II type 1 (AT1) receptor in the infarcted heart. Liposomes 142 nm in diameter were conjugated with a ligand specific to AT1. The nanoparticles were able to specifically target cardiac cells in vitro, and in the infarcted heart after intravenous injection in vivo. This system may be useful for delivering therapeutic agents specifically to the infarcted heart.

Angiogenesis in ischemic tissue produced by spheroid grafting of human adipose-derived stromal cells

Stem cells offer significant therapeutic promise for the treatment of ischemic disease. However, stem cells transplanted into ischemic tissue exhibit limited therapeutic efficacy due to poor engraftment in vivo. Several strategies for improving the survival and engraftment of stem cells in ischemic tissue have been developed including transplantation in combination with growth factor delivery, genetic modification of stem cells, and the use of cell-transplantation scaffolds. Here, we demonstrate that human adipose-derived stromal cells (hADSCs) cultured and grafted as spheroids exhibit improved therapeutic efficacy for ischemia treatment. hADSCs were cultured in monolayer or spheroids. Spheroid cultures were more effective in preconditioning hADSCs to a hypoxic environment, upregulating hypoxia-adaptive signals (i.e., stromal cell-derived factor-1α and hypoxia-inducible factor-1α), inhibiting apoptosis, and enhancing secretion of both angiogenic and anti-apoptotic factors (i.e., hepatocyte growth factor, vascular endothelial growth factor, and fibroblast growth factor 2) compared to monolayer cultures. Moreover, cell harvesting following spheroid cultures avoided damage to extracellular matrices due to harsh proteolytic enzyme treatment, thereby preventing anoikis (apoptosis induced by a lack of cell-matrix interaction). Following intramuscular transplantation to ischemic hindlimbs of athymic mice, hADSC spheroids showed improved cell survival, angiogenic factor secretion, neovascularization, and limb survival as compared to hADSCs grafted as dissociated cells. Taken together, spheroid cultures precondition hADSCs to a hypoxic environment, and grafting hADSCs as spheroids to ischemic limbs improves therapeutic efficacy for ischemia treatment due to enhanced cell survival and paracrine effects. Spheroid-based cell delivery could be a simple and effective strategy for improving stem cell therapy for ischemic diseases, eliminating the need for growth factor delivery, biomaterial scaffolds or genetic modification.