Hemostatic and Absorbent PolyHIPE-Kaolin Composites for 3D Printable Wound Dressing Materials.

A novel hemostatic and absorbent wound dressing material compatible with 3D printing is developed to address deficiencies in current wound dressing protocol. The design involves an open celled, microporous hydrogel foam via a high internal phase emulsion (HIPE) template with biocompatible components and tunable hemostatic character by kaolin loading, the viscosity and cure kinetics of which are tailored for 3D printing applications. The use of nontoxic mineral oil organic phase results in cytocompatability with human dermal fibroblasts.

Mechanical stabilization of proteolytically degradable polyethylene glycol dimethacrylate hydrogels through peptide interaction.

Unlabelled: Balancing enhancement of neurite extension against loss of matrix support in synthetic hydrogels containing proteolytically degradable and bioactive signaling peptides to optimize tissue formation is difficult. Using a systematic approach, polyethylene glycol hydrogels containing concurrent continuous concentration gradients of the laminin derived bioactive signaling peptide, Ile-Lys-Val-Ala-Val (IKVAV), and collagen derived matrix metalloprotease degradable peptide, GPQGIWGQ, were fabricated and characterized. During proteolytic degradation of the concentration gradient hydrogels, the IKVAV and IWGQ cleavage fragment from GPQGIWGQ were found to interact and stabilize the bulk Young's Modulus of the hydrogel.

Effects of free radical initiators on polyethylene glycol dimethacrylate hydrogel properties and biocompatibility.

Many studies have utilized Irgacure 2959 photopolymerized poly(ethylene glycol) (PEG) hydrogels for tissue engineering application development. Due to the limited penetration of ultraviolet light through tissue, Irgacure 2959 polymerized hydrogels are not suitable for use in tissues where material injection is desirable, such as the spinal cord. To address this, several free radical initiators (thermal initiator VA044, ammonium persulfate (APS)/TEMED reduction-oxidation reaction, and Fenton chemistry) are evaluated for their effects on the material and mechanical properties of PEG hydrogels compared with Irgacure 2959.

Human Induced Pluripotent Stem Cell Derived Neural Stem Cell Survival and Neural Differentiation on Polyethylene Glycol Dimethacrylate Hydrogels Containing a Continuous Concentration Gradient of -Cadherin Derived Peptide His-Ala-Val-Asp-Ile.

Although preclinical models of spinal cord injury have shown that matrix inclusion in stem cell therapy leads to greater neurological improvements than that including cells alone, there has been insufficient matrix optimization for human cells. -Cadherin influences the development and maintenance of neural tissue, but the effects of -cadherin derived peptide His-Ala-Val-Asp-Ile (HAVDI) on the survival, neurite extension, and expression of neural differentiation markers in human induced pluripotent stem cell derived neural stems (hNSC) have not been widely examined. Using polyethylene glycol hydrogels containing a continuous gradient of HAVDI, this study identifies concentration dependent effects on hNSC survival and neural differentiation.

Response to di-functionalized hyaluronic acid with orthogonal chemistry grafting at independent modification sites in rodent models of neural differentiation and spinal cord injury.

Hyaluronic acid (HA) with one reactive moiety grafted to the backbone is a commonly used matrix in tissue engineering. The addition of a second orthogonal moiety to the backbone allows for greater control in bioactive signal tethering and gelation. In this study, thiol and azide functional groups were grafted to the HA backbone at separate modification sites.

Stem cells for spinal cord injury: Strategies to inform differentiation and transplantation.

The complex pathology of spinal cord injury (SCI), involving a cascade of secondary events and the formation of inhibitory barriers, hampers regeneration across the lesion site and often results in irreversible loss of motor function. The limited regenerative capacity of endogenous cells after SCI has led to a focus on the development of cell therapies that can confer both neuroprotective and neuroregenerative benefits. Stem cells have emerged as a candidate cell source because of their ability to self-renew and differentiate into a multitude of specialized cell types.

Combination therapy of stem cell derived neural progenitors and drug delivery of anti-inhibitory molecules for spinal cord injury.

Unlabelled: Regeneration of lost synaptic connections following spinal cord injury (SCI) is limited by local ischemia, cell death, and an excitotoxic environment, which leads to the development of an inhibitory glial scar surrounding a cystic cavity. While a variety of single therapy interventions provide incremental improvements to functional recovery after SCI, they are limited; a multifactorial approach that combines several single therapies may provide a better chance of overcoming the multitude of obstacles to recovery. To this end, fibrin scaffolds were modified to provide sustained delivery of neurotrophic factors and anti-inhibitory molecules, as well as encapsulation of embryonic stem cell-derived progenitor motor neurons (pMNs).

Sustained dual drug delivery of anti-inhibitory molecules for treatment of spinal cord injury.

Myelin-associated inhibitors (MAIs) and chondroitin sulfate proteoglycans (CSPGs) are major contributors to axon growth inhibition following spinal cord injury and limit functional recovery. The NEP1-40 peptide competitively binds the Nogo receptor and partially blocks inhibition from MAIs, while chondroitinase ABC (ChABC) enzymatically digests CSPGs, which are upregulated at the site of injury. In vitro studies showed that the combination of ChABC and NEP1-40 increased neurite extension compared to either treatment alone when dissociated embryonic dorsal root ganglia were seeded onto inhibitory substrates containing both MAIs and CSPGs.