Cord blood platelet rich plasma (PRP) as a potential alternative to autologous PRP for allogenic preparation and regenerative applications.

As an abundant supplier of growth factors, chemokines and other bioactive molecules, platelet rich plasma (PRP) become a leading therapy for tissue regeneration. The PRP therapy is an inexpensive and feasible source of growth factor compared to commercial products however, the better source of platelets is the major challenge. Many researchers are skeptical about cord blood as an alternative source for the allogenic preparation of PRP. In the present study, we have compared adult peripheral and cord blood PRP for their regenerative capacity and immuno-modulatory nature. ELISA data indicates that the cord PRP contained a considerably higher amount of growth factors compared to adult PRP. In-vitro results indicate a significant increase in cell proliferation and migration with cord PRP treatment. The immunomodulatory evaluation shows cord blood PRP has better potential in switching activated macrophages to anti-inflammatory markers when compared with adult PRP, as well as the cytokines production indicates a significant reduction in the release of IFN-γ in cord PRP treatment. The study shows the beneficial effects of using cord blood PRP over adult PRP however, future studies are required to validate cord blood PRP as a permanent source for regenerative therapy.

Airbrushed nanofibers with bioactive core and antibacterial shell for wound healing application.

Acute and chronic wounds are vulnerable to infection and delayed healing and require critical care and advanced wound protection. To overcome the challenges, dual therapy of antibacterial and growth factors will be a novel wound care strategy. The present study explores airbrushed core-shell nanofiber for dual delivery of epidermal growth factor (EGF) and amoxicillin (AMOX) in a sustained manner. A blend of polycaprolactone (PCL)-polyethylene oxide (PEO) was used to prepare the shell compartment for amoxicillin loading and poly-DL-lactide (PDLLA) core for EGF loading by using a customized airbrush setup. Characterization result shows a uniform distribution of nanofibers ranging between 200 and 500 nm in diameter. Amoxicillin loading in the shell compartment offers an initial burst release followed by a sustained release for up to 14 days. Whereas EGF in the core part shows a continuous sustained release throughout the release study.In-vitrostudy indicates the biocompatibility of EGF-AMOX loaded core-shell nanofibers with human dermal fibroblast cell (HDF) cells and a higher cellular proliferation compared to control samples. Gene expression data show an increase in fold change of collagen I and tropoelastin expression, indicating the regenerative properties of EGF-AMOX encapsulated nanofiber. The combination of bioactive core (EGF) and antibiotic shell (amoxicillin) in an airbrushed nanofibrous scaffold is a novel approach, which is the first time explored to deliver sustainable therapy to treat skin wounds. Our results demonstrate that PCL-PEO-Amoxicillin/PDLLA-EGF-loaded core-shell nanofibers are promising dual therapy scaffolds to deliver effective skin wound care, with the possibility of direct deposition on the wound.

Ultrashort Peptide-Based Hydrogel for the Healing of Critical Bone Defects in Rabbits.

The use of hydrogels as scaffolds for three-dimensional (3D) cell growth is an active area of research in tissue engineering. Herein, we report the self-assembly of an ultrashort peptide, a tetrapeptide, Asp-Leu-IIe-IIe, the shortest peptide sequence from a highly fibrillogenic protein TDP-43, into the hydrogel. The hydrogel was mechanically strong and highly stable, with storage modulus values in MPa ranges. The hydrogel supported the proliferation and successful differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in its matrix as assessed by cell viability, calcium deposition, alkaline phosphatase (ALP) activity, and the expression of osteogenic marker gene studies. To check whether the hydrogel supports 3D growth and regeneration in in vivo conditions, a rabbit critical bone defect model was used. Micro-computed tomography (CT) and X-ray analysis demonstrated the formation of mineralized neobone in the defect areas, with significantly higher bone mineralization and relative bone densities in animals treated with the peptide hydrogel compared to nontreated and matrigel treatment groups. The ultrashort peptide-based hydrogel developed in this work holds great potential for its further development as tissue regeneration and/or engineering scaffolds.

Silver sulfadiazine loaded core-shell airbrushed nanofibers for burn wound healing application.

Ideal dressing materials for complex and large asymmetric burns should have the dual properties of anti-bacterial and regenerative with advanced applicability of direct deposit on the wound at the patient bedside. In this study, core-shell nanofibers (polycaprolactone; PCL and polyethylene oxide; PEO) with different percent of silver sulfadiazine (SSD) loading (2-10%) were prepared by the airbrushing method using a custom build device. Results indicate a sustained release profile of silver sulfadiazine (SSD) up to 28 days and concentration-dependent anti-bacterial activity. The morphology and proliferation of human dermal fibroblast (HDF) cells and human dental follicle stem cells (HDFSC) on the silver sulfadiazine loaded nanofibers confirm the biocompatibility of airbrushed nanofibers. Moreover, upregulation of extracellular matrix (ECM) proteins (Col I, Col III, and elastin) support the differentiation and regenerative properties of silver sulfadiazine nanofiber mats. This was further confirmed by the complete recovery of rabbit burn wound models within 7 days of silver sulfadiazine loaded nanofiber dressing. Histopathology data show silver sulfadiazine loaded core-shell nanofibers' anti-inflammatory and proliferative activity without any adverse response on the tissue. Overall data display that the airbrushed silver sulfadiazine-loaded core-shell nanofibers are effective dressing material with the possibility of direct fiber deposition on the wound to cover, heal, and regenerate large asymmetric burn wounds.

Cell encapsulated and microenvironment modulating microbeads containing alginate hydrogel system for bone tissue engineering.

Functional tissue regeneration using synthetic biomaterials requires proliferation and heterotypic differentiation of stem/progenitor cells within a specialized heterogeneous (biophysical-biochemical) microenvironment. The current techniques have limitations to develop synthetic hydrogels, mimicking native extracellular matrix porosity along with heterogeneous microenvironmental cues of matrix mechanics, degradability, microstructure and cell-cell interactions. Here, we have developed a microenvironment modulating system to fabricate in situ porous hydrogel matrix with two or more distinct tailored microenvironmental niches within microbeads and the hydrogel matrix for multicellular tissue regeneration. Electrosprayed pectin-gelatin blended microbeads and crosslinked alginate hydrogel system help to tailor microenvironmental niches of encapsulated cells where two different cells are surrounded by a specific microenvironment. The effect of different microenvironmental parameters associated with the microbead/hydrogel matrix was evaluated using human umbilical-cord mesenchymal stem cells (hUCMSCs). The osteogenic differentiation of hUCMSCs in the hydrogel matrix was evaluated for bone tissue regeneration. This will be the first report on microenvironment modulating microbead-hydrogel system to encapsulate two/more types of cells in a hydrogel, where each cell is surrounded with distinct niches for heterogeneous tissue regeneration.

Development of Dual Drug Eluting Cardiovascular Stent with Ultrathin Flexible Poly(l-lactide-co-caprolactone) Coating.

The pleiotropic effects of the atorvastatin-fenofibrate combination can be effectively harnessed for site-specific therapy to minimize stent-related complications. The present study aims to utilize the pleiotropic effects of these two drugs entrapped in a uniform and defect-free coating of poly(l-lactide-co-caprolactone) (PLCL) on a stainless steel stent to overcome stent-associated limitations. The stent coating parameters were optimized using ultrasonic spray coating technique to achieve a thin, smooth, and defect-free dual drug-loaded polymer coating on the stent. The dual drug-loaded polymer coated stent was characterized for surface morphology, thickness and coating integrity. In vitro drug release kinetics of the fabricated stent reveals a sustained release of both drugs for more than 60 days. Significant reduction of thrombus formation and adhesion of lipopolysaccharide-stimulated macrophages on the dual drug containing polymer-coated stent indicates that the drug combination possesses antithrombotic and anti-inflammatory effects. The combination did not adversely influence endothelialization but significantly retarded smooth muscle cell proliferation indicating its potential to overcome restenosis. No bacterial biofilm formation was observed on the stent due to the antibacterial activity of atorvastatin. A rat subcutaneous model was used to evaluate the biocompatibility of the coated stent and compared with the commercial stent. MicroCT, scanning electron microscopy, and morphometric analyses revealed that the coated stents exhibited excellent histocompatibility with no inflammatory response as evidenced from the cytokine levels measured 28 days postimplantation. Our data demonstrates for the first time that the combination of atorvastatin and fenofibrate can be successfully employed in cardiovascular stents to overcome the current limitations of conventional drug-eluting stents.

Harnessing the pleiotropic effects of atorvastatin-fenofibrate combination for cardiovascular stents.

Atorvastatin and fenofibrate have been conventionally employed as lipid-lowering agents. They also exhibit beneficial effects in the treatment of endothelial dysfunction, oxidative stress and vascular inflammation due to their pleiotropic effects that include vasodilatory and anti-inflammatory effects. These pleiotropic effects may serve to overcome the drawbacks of late stent thrombosis and delayed endothelialization that plague conventional drug eluting stents. However, the combination has not been explored yet as therapeutic coatings in drug eluting stents. The present study aims to investigate the potential of atorvastatin-fenofibrate combination loaded in a biodegradable poly(l-lactide-co-caprolactone) polymer film to inhibit thrombus formation and macrophage activation apart from exploring their effect on the proliferation of smooth muscle cells and endothelial cells. The dual drug-loaded polymer films were characterized by spectroscopy and calorimetry. In vitro studies revealed that the combination effectively retarded the proliferation of only smooth muscle cells but not the endothelial cells which augers well for stent applications where rapid re-endothelialization is preferred. Further, the dual drug-loaded films exhibited a marked decrease in the adhesion and activation of platelets and macrophages revealing the potent anti-thrombogenic and anti-inflammatory effects of the combination. The pleiotropic effects of the combination may be attributed to their ability to activate nitric oxide synthase in endothelial cells while mTOR levels remained unaltered by the combination.