Therapeutic Efficacy of Cryopreserved, Allogeneic Extracellular Vesicles for Treatment of Acute Myocardial Infarction.

Extracellular vesicles (EV) that are derived from endothelial progenitor cells (EPC) have been determined to be a novel therapy for acute myocardial infarction, with a promise for immediate "off-the-shelf" delivery. Early experience suggests delivery of EVs from allogeneic sources is safe. Yet, clinical translation of this therapy requires assurances of both EV stability following cryopreservation and absence of an adverse immunologic response to EVs from allogeneic donors. Thus, more bioactivity studies on allogeneic EVs after cold storage are necessary to establish quality standards for its widespread clinical use. Thus, in this study, we aimed to demonstrate the safety and efficacy in delivering cryopreserved EVs in allogeneic recipients as a therapy for acute myocardial infarction.In this present study, we have analyzed the cardioprotective effects of allogeneic EPC-derived EVs after storage at -80°C for 2 months, using a shear-thinning gel (STG) as an in vivo delivery vehicle. EV size, proteome, and nucleic acid cargo were observed to remain steady through extended cryopreservation via nanoparticle tracking analysis, mass spectrometry, and nanodrop analysis, respectively. Fresh and previously frozen EVs in STG were delivered intramyocardially in a rat model of myocardial infarction (MI), with both showing improvements in contractility, angiogenesis, and scar thickness in comparison to phosphate-buffered saline (PBS) and STG controls at 4 weeks post-MI. Pathologic analyses and flow cytometry revealed minimal inflammatory and immune upregulation upon exposure of tissue to EVs pooled from allogeneic donor cells.Allogeneic EPC-EVs have been known to elicit minimal immune activity and retain therapeutic efficacy after at least 2 months of cryopreservation in a post-MI model.

Facilitating safe and sustained submucosal lift through an endoscopically injectable shear-thinning carboxymethyl starch sodium hydrogel.

Traditional submucosal filling materials frequently show insufficient lifting height and duration during clinical procedures. Here, the anionic polysaccharide polymer sodium carboxymethyl starch and cationic Laponite to prepare a hydrogel with excellent shear-thinning ability through physical cross-linking, so that it can achieve continuous improvement of the mucosal cushion through endoscopic injection. The results showed that the hydrogel (56.54 kPa) had a lower injection pressure compared to MucoUp (68.56 kPa). The height of submucosal lifting height produced by hydrogel was higher than MucoUp, and the height maintenance ability after 2 h was 3.20 times that of MucoUp. At the same time, the hydrogel also showed satisfactory degradability and biosafety, completely degrading within 200 h. The hemolysis rate is as low as 0.76 %, and the cell survival rate > 80 %. Subcutaneous implantation experiments confirmed that the hydrogel showed no obvious systemic toxicity. Animal experiments clearly demonstrated the in vivo feasibility of using hydrogels for submucosal uplift. Furthermore, successful endoscopic submucosal dissection was executed on a live pig stomach, affirming the capacity of hydrogel to safely and effectively facilitate submucosal dissection and mitigate adverse events, such as bleeding. These results indicate that shear-thinning hydrogels have a wide range applications as submucosal injection materials.

Shear-thinning hydrogel for allograft cell transplantation and externally controlled transgene expression.

This work establishes the design of a fully synthetic, shear-thinning hydrogel platform that is injectable and can isolate engineered, allogeneic cell therapies from the host. We utilized RAFT to generate a library of linear random copolymers of N,N-dimethylacrylamide (DMA) and 2-vinyl-4,4-dimethyl azlactone (VDMA) with variable mol% VDMA and degree of polymerization. Poly(DMA-co-VDMA) copolymers were subsequently modified with either adamantane (Ad) or ß-cyclodextrin (Cd) through amine-reactive VDMA to prepare hydrogel precursor macromers containing complementary guest-host pairing pendant groups that, when mixed, form shear-thinning hydrogels. Rheometric evaluation of the hydrogel library enabled identification of lead macromer structures comprising 15 mol% pendants (Ad or Cd) and a degree of polymerization of 1000; mixing of these Ad and Cd functionalized precursors yielded hydrogels possessing storage modulus above 1000 Pa, tan(δ) values below 1 and high yield strain, which are target characteristics of robust but injectable shear-thinning gels. This modular system proved amenable to nanoparticle integration with surface-modified nanoparticles displaying Ad. The addition of the Ad-functionalized nanoparticles simultaneously improved mechanical properties of the hydrogels and enabled extended hydrogel retention of a model small molecule in vivo. In studies benchmarking against alginate, a material traditionally used for cell encapsulation, the lead hydrogel showed significantly less fibrous encapsulation in a subcutaneous implant site. Finally, this platform was utilized to encapsulate and extend in vivo longevity of inducible transgene-engineered mesenchymal stem cells in an allogeneic transplant model. The hydrogels remained intact and blocked infiltration by host cells, consequently extending the longevity of grafted cell function relative to a benchmark, shear-thinning hyaluronic acid-based gel. In sum, the new synthetic, shear-thinning hydrogel system presented here shows potential for further development as an injectable platform for delivery and in situ drug modulation of allograft and engineered cell therapies.

A Drug-Eluting Injectable NanoGel for Localized Delivery of Anticancer Drugs to Solid Tumors.

Systemically administered chemotherapy reduces the efficiency of the anticancer agent at the target tumor tissue and results in distributed drug to non-target organs, inducing negative side effects commonly associated with chemotherapy and necessitating repeated administration. Injectable hydrogels present themselves as a potential platform for non-invasive local delivery vehicles that can serve as a slow-releasing drug depot that fills tumor vasculature, tissue, or resection cavities. Herein, we have systematically formulated and tested an injectable shear-thinning hydrogel (STH) with a highly manipulable release profile for delivering doxorubicin, a common chemotherapeutic. By detailed characterization of the STH physical properties and degradation and release dynamics, we selected top candidates for testing in cancer models of increasing biomimicry. Two-dimensional cell culture, tumor-on-a-chip, and small animal models were used to demonstrate the high anticancer potential and reduced systemic toxicity of the STH that exhibits long-term (up to 80 days) doxorubicin release profiles for treatment of breast cancer and glioblastoma. The drug-loaded STH injected into tumor tissue was shown to increase overall survival in breast tumor- and glioblastoma-bearing animal models by 50% for 22 days and 25% for 52 days, respectively, showing high potential for localized, less frequent treatment of oncologic disease with reduced dosage requirements.

A shear-thinning, ROS-scavenging hydrogel combined with dental pulp stem cells promotes spinal cord repair by inhibiting ferroptosis.

Spinal cord injury (SCI) is a serious clinical disease. Due to the deformability and fragility of the spinal cord, overly rigid hydrogels cannot be used to treat SCI. Hence, we used TPA and Laponite to develop a hydrogel with shear-thinning ability. This hydrogel exhibits good deformation, allowing it to match the physical properties of the spinal cord; additionally, this hydrogel scavenges ROS well, allowing it to inhibit the lipid peroxidation caused by ferroptosis. According to the in vivo studies, the TPA@Laponite hydrogel could synergistically inhibit ferroptosis by improving vascular function and regulating iron metabolism. In addition, dental pulp stem cells (DPSCs) were introduced into the TPA@Laponite hydrogel to regulate the ratios of excitatory and inhibitory synapses. It was shown that this combination biomaterial effectively reduced muscle spasms and promoted recovery from SCI.

Nanoengineered Shear-Thinning Hydrogel Barrier for Preventing Postoperative Abdominal Adhesions.

More than 90% of surgical patients develop postoperative adhesions, and the incidence of hospital re-admissions can be as high as 20%. Current adhesion barriers present limited efficacy due to difficulties in application and incompatibility with minimally invasive interventions. To solve this clinical limitation, we developed an injectable and sprayable shear-thinning hydrogel barrier (STHB) composed of silicate nanoplatelets and poly(ethylene oxide). We optimized this technology to recover mechanical integrity after stress, enabling its delivery though injectable and sprayable methods. We also demonstrated limited cell adhesion and cytotoxicity to STHB compositions in vitro. The STHB was then tested in a rodent model of peritoneal injury to determine its efficacy preventing the formation of postoperative adhesions. After two weeks, the peritoneal adhesion index was used as a scoring method to determine the formation of postoperative adhesions, and STHB formulations presented superior efficacy compared to a commercially available adhesion barrier. Histological and immunohistochemical examination showed reduced adhesion formation and minimal immune infiltration in STHB formulations. Our technology demonstrated increased efficacy, ease of use in complex anatomies, and compatibility with different delivery methods, providing a robust universal platform to prevent postoperative adhesions in a wide range of surgical interventions.

Dipeptide Self-assembled Hydrogels with Shear-Thinning and Instantaneous Self-healing Properties Determined by Peptide Sequences.

Dipeptide self-assembled hydrogels have potential biomedical applications because of their great biocompatibility, bioactivity, and tunable physicochemical properties, which can be modulated in the molecular level by design of amino acid sequences. Herein, a series of dipeptides (Fmoc-FL, -YL, -LL, and -YA) are designed to form shear-thinning hydrogels with self-healing and tunable mechanical properties by adjusting the synergetic effect of hydrophobic interactions (π-π stacking and hydrophobic effect) and hydrogen bonds of peptides through substitution of amino acid residues. The enhancement of hydrophobic interactions is a primary factor to promote mechanical rigidity of hydrogels, and strong hydrogen-bonding interactions between molecules contribute to the instantaneous self-healing property, which is supported by experimental studies (FTIR, CD, SEM, AFM, and rheology) and molecular dynamics simulations. The injectable dipeptide hydrogels were certified as an ideal endoscopic submucosal dissection filler to make operation convenient and secure in mice and living mini-pig's experiments with a longer duration time, higher stiffness, and lower inflammatory response than commercial clinical fillers.

Cold Chain-Free Storable Hydrogel for Infant-Friendly Oral Delivery of Amoxicillin for the Treatment of Pneumococcal Pneumonia.

Pneumonia is the major cause of death in children under five, particularly in developing countries. Antibiotics such as amoxicillin greatly help in mitigating this problem. However, there is a lack of an infant/toddler-friendly formulation for countries with limited clean water orr electricity. Here, we report the development of a shear-thinning hydrogel system for the oral delivery of amoxicillin to infant/toddler patients, without the need of clean water and refrigeration. The hydrogel formulation consists of metolose (hydroxypropyl methylcellulose) and amoxicillin. It preserves the structural integrity of antibiotics and their antibacterial activity over 12 weeks at room temperature. Pharmacokinetic profiling of mice reveals that the hydrogel formulation increases the bioavailability of drugs by ∼18% compared to that with aqueous amoxicillin formulation. More importantly, oral gavage of this formulation in a mouse model of secondary pneumococcal pneumonia significantly ameliorates inflammatory infiltration and tissue damage in lungs, with a 10-fold reduction in bacterial counts compared to those in untreated ones. Given the remarkable antibacterial efficacy as well as the use of FDA-regulated ingredients (metolose and amoxicillin), the hydrogel formulation holds great promise for rapid clinical translation.