Potential of a novel scaffold composed of human platelet lysate and fibrin for human corneal endothelial cells

Cell-based therapies have been emerged to find innovative solutions for corneal endothelial dysfunction. The aim of this study is to investigate the suitability of a blended scaffold containing human platelet lysate (HPL) and fibrin not only for cultivating human corneal endothelial cells (HCECs) but also for serving as a scaffold for the respected cells. We isolated HCECs from human donors and encapsulated the cells with three concentrations of HPL/Fibrin scaffold, namely HPL/Fibrin 1, HPL/Fibrin 2 and HPL/Fibrin 3, by adding 28.9, 57.8 and 86.7 mg/dl of fibrinogen to HPL to obtain a final percentage of 10, 20 and 30 % of fibrinogen, respectively. SEM imaging and swelling test were done to characterize the scaffolds. Cell viability assay and cell counting were performed on the cells. HCECs were characterized by morphology and immunocytochemistry. SEM imaging on freeze-dried scaffolds showed higher porosity of HPL/Fibrin 1 and HPL/Fibrin 2 than HPL/Fibrin 3, but larger pores were observed only in HPL/Fibrin 1. Cellular attachment and morphology on HPL/Fibrin 1 were appropriate by SEM imaging. A higher swelling rate was observed in HPL/Fibrin 1. After 3 and 5 days, higher numbers of cells were observed specifically in HPL/Fibrin 1. A higher expression of Na+/K+-ATPase, ZO-1 and vimentin proteins was detected in the HPL/Fibrin 1-cultured HCECs as compared with control (no scaffold). HPL/Fibrin can be used as a suitable scaffold for HCECs while preserving the cells viability. Further investigations are necessitated to approve the beneficial effects of the suggested scaffold for delivering and transplantation of cultivated HCECs into the anterior chamber of the eye.

Infarct Zone: a Novel Platform for Exosome Trade in Cardiac Tissue Regeneration

The global incidence of coronary artery diseases (CADs), especially myocardial infarction (MI), has drastically increased in recent years. Even though the conventional therapies have improved the outcomes, the post-MI complications and the increased rate of recurrence among the survivors are still alarming. Molecular events associated with the pathogenesis and the adaptive responses of the surviving myocardium are largely unknown. Focus on exosome-mediated signaling for cell-cell/matrix communications at the infarct zone reflects an emerging opportunity in cardiac regeneration. Also, cardiac tissue engineering provides promising insights for the next generation of therapeutic approaches in the management of CADs. In this article, we critically reviewed the current understanding on the biology of cardiac exosomes, therapeutic potential of exosomes, and recent developments in cardiac tissue engineering and discussed novel translational approaches based on tissue engineering and exosomes for cardiac regeneration and CADs.

Evaluating the biocompatibility of marine-derived chitosan–collagen polymeric blends for biomedical applications

The capability of biomaterials such as chitosan and collagen to support cell growth and proliferation makes them promising candidates in biomedical applications. Chitosan and collagen from marine world have already been proved to be better alternatives to those from terrestrial world. In the current study, chitosan and collagen were isolated from shrimp shell and fish skin, respectively. The polymers were characterized by ultraviolet-visible spectra analysis, Fourier transform infrared-attenuated total reflectance analysis, CHN analysis, and sodium dodedcyl sulfate polyacrylamide gel electrophoresis analysis. Interpenetrating blends of these polymers were synthesized in the form of films in two different ratios. Glutaraldehyde was used as an additional cross-linker to provide more stability to the blends. The polymeric blends were also characterized by Fourier transform infrared-attenuated total reflectance, scanning electron microscopy analysis, and swelling studies. The biocompatibility evaluation included hemocompatibility and cytocompatibility studies. Fourier transform infrared-attenuated total reflectance analysis of films confirmed the presence of characteristic functional groups and molecular interactions of the two polymers in the two blends. Homogenous blending of the two biopolymers in both film compositions was confirmed by the smooth surface images in scanning electron microscopy analysis. The swelling study revealed that both the films can effectively transfer water across it, hence nutrients and waste materials. During hemocompatibility evaluations, no red blood cell aggregation was observed and both the films adsorbed plasma proteins, predominantly albumin, when they made contact with blood. Although one of the films showed slightly higher hemolysis, the value was within the acceptable range. More than 90% viability obtained in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay shows the non-toxic nature of the two films. No sign of morphological changes to L929 cells was seen when they were in direct contact with both films. Live/dead assay using acridine orange/ethidium bromide cocktail showed that the films have not induced apoptosis to the L929 cells, which further asserts their biocompatible nature.

Injectable, cytocompatible, elastic, free radical scavenging and electroconductive hydrogel for cardiac cell encapsulation

The injectable electroconductive hydrogels are desirable for the regenerative therapy of electroresponsive tissues like heart. With the present electroconductive hydrogels, the issues of cytotoxicity, biodegradability, and diffusion of the conductive element and poor water solubility limit their applications. Here, electroconductive injectable single component hydrogels, PANIE-P/PEGDA and PANIS-P/PEGDA, are prepared with fumarate-co-PEG-co-sebacate comacromer conjugated with non-sulfonated/sulfonated polyaniline and PEGDA. These hydrogels have maximum electrical conductivity of 0.351±0.043×10^-3Scm^-1 and 0.550±0.016×10^-3Scm^-1, which is comparable to the native myocardium. The hydrogels with 50% comacromer concentration coded as PE50P and PS50P retain 82.48% and 84.08% water on equilibrium swelling respectively. The hydrogels have required a porous surface for cell growth and proliferation. PS50P hydrogel has stiffness of 442kPa with elastic characteristics. The hydrogel is compatible with L929 fibroblast and H9c2 cardiomyoblast cells. PS50P hydrogel has better free radical scavenging property and protective effect over cells under oxidative stress. The hydrogel retains encapsulated cardiomyoblast cells with 98% viability under static long-term in vitro culture. Briefly, the PS50P hydrogel is electroconductive, free radical scavenging and mechanically suitable for cardiac regenerative therapy.

Design, preparation and characterization of pH-responsive prodrug micelles with hydrolyzable anhydride linkages for controlled drug delivery

We report a new prodrug micelle-based approach in which a model hydrophobic non-steroidal anti-inflammatory drug (NSAID), ibuprofen (Ibu), is tethered to amphiphilic methoxy polyethylene glycol-polypropylene fumarate (mPEG-PPF) diblock copolymer via hydrolytic anhydride linkages for potential controlled release applications of NSAIDs. Synthesized mPEG-PPF-Ibu polymer drug conjugates (PDCs) demonstrated high drug conjugation efficiency (∼90%) and self-assembled to form micellar nanostructures in aqueous medium with critical micelle concentrations ranging between 16 and 30μg/mL. The entrapment efficiency of Ibu in prepared PDC micelles was as high as 18% (w/w). Crosslinking of prodrug micelles with N,N'-dimethylaminoethyl methacrylate conferred pH-responsive characteristics. pH-responsive PDC micelles averaged 100nm in size at pH 7.4 and exhibited concomitant changes in size upon incubation in physiologically relevant mildly acidic conditions. Ibu release was observed to increase with increasing acidic conditions and could be controlled by varying the amount of crosslinker used. Furthermore, the prepared mPEG-PPF-based micelles demonstrated excellent cytocompatibility and cellular internalization in vitro. More importantly, PDC micelles exerted anti-inflammatory effects by significantly decreasing monosodium urate crystal-induced prostaglandin E2 levels in rabbit synoviocyte cultures in vitro. Cumulatively, our results indicate that this new prodrug micelle approach is promising for NSAID-based therapies in the treatment of arthritis and cancer.

In situ crosslinkable elastomeric hydrogel for long-term cell encapsulation for cardiac applications

The regenerative therapy of tissues relays on successful cell transplantation and engraftment. Soft hydrogel carriers are employed to protect transplanted cells from harmful microenvironment in soft tissue regeneration. Herein an injectable, porous, biodegradable, bioresorbable, and elastomeric hydrogel fabricated from poly(propylene fumarate-co-sebacate-co-ethylene glycol) crosslinked with PEGDA for cardiomyoblast encapsulation was reported. The hydrogel retains adequate mechanical property in the range of native myocardium even after 30 days of degradation (49 ± 0.008 kPa). The hydrogel shows maximum extensibility without collapsing even under 60% compression. The hydrogel retains 70.58% equilibrium water content, wide internal porosity, and slow bulk degradation favorable for cell carriers. The cardiomyoblast cells encapsulated in hydrogel retains viability even after 30 days of culture. The long-term viability and proliferation studies of encapsulated cells in the hydrogel substantiate the suitability of hydrogel microenvironment for cell survival. The present hydrogel is a potential cell carrier with favorable physical and biological properties for cell encapsulation for cardiac applications. The candidate hydrogels perform better than the other reported elastomeric hydrogels fabricated for cell therapy. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2936-2944, 2016.

Stem cells and injectable hydrogels: Synergistic therapeutics in myocardial repair

One of the major problems in the treatment of cardiovascular diseases is the inability of myocardium to self-regenerate. Current therapies are unable to restore the heart's function after myocardial infarction. Myocardial tissue engineering is potentially a key approach to regenerate damaged heart muscle. Myocardial patches are applied surgically, whereas injectable hydrogels provide effective minimally invasive approaches to recover functional myocardium. These hydrogels are easily administered and can be either cell free or loaded with bioactive agents and/or cardiac stem cells, which may apply paracrine effects. The aim of this review is to investigate the advantages and disadvantages of injectable stem cell-laden hydrogels and highlight their potential applications for myocardium repair.