Production and Characterization of Chemically Cross-Linked Collagen Scaffolds

Dual drug delivery collagen vehicles for modulation of skin fibrosisin vitro

Single molecule drug delivery systems have failed to yield functional therapeutic outcomes, triggering investigations into multi-molecular drug delivery vehicles. In the context of skin fibrosis, although multi-drug systems have been assessed, no system has assessed molecular combinations that directly and specifically reduce cell proliferation, collagen synthesis and transforming growth factor β1 (TGFβ1) expression. Herein, a core-shell collagen type I hydrogel system was developed for the dual delivery of a TGFβ trap, a soluble recombinant protein that inhibits TGFβ signalling, and Trichostatin A (TSA), a small molecule inhibitor of histone deacetylases. The antifibrotic potential of the dual delivery system was assessed in an in vitro skin fibrosis model induced by macromolecular crowding (MMC) and TGFβ1. SDS-PAGE and HPLC analyses revealed that ~ 50 % of the TGFβ trap and ~ 30 % of the TSA were released from the core and shell compartments, respectively, of the hydrogel system after 10 days (longest time point assessed) in culture. As a direct consequence of this slow release, the core (TGFβ trap) / shell (TSA) hydrogel system induced significantly (p < 0.05) lower than the control group (MMC and TGFβ1) collagen type I deposition (assessed via SDS-PAGE and immunocytochemistry), α smooth muscle actin (αSMA) expression (assessed via immunocytochemistry) and cellular proliferation (assessed via DNA quantification) and viability (assessed via calcein AM and ethidium homodimer-I staining) after 10 days in culture. On the other hand, direct TSA-TGFβ supplementation induced the lowest (p < 0.05) collagen type I deposition, αSMA expression and cellular proliferation and viability after 10 days in culture. Our results illustrate the potential of core-shell collagen hydrogel systems for sustained delivery of antifibrotic molecules.

HATMSC Secreted Factors in the Hydrogel as a Potential Treatment for Chronic Wounds-In Vitro Study

Mesenchymal stem cells (MSCs) can improve chronic wound healing; however, recent studies suggest that the therapeutic effect of MSCs is mediated mainly through the growth factors and cytokines secreted by these cells, referred to as the MSC secretome. To overcome difficulties related to the translation of cell therapy into clinical use such as efficacy, safety and cost, we propose a hydrogel loaded with a secretome from the recently established human adipose tissue mesenchymal stem cell line (HATMSC2) as a potential treatment for chronic wounds. Biocompatibility and biological activity of hydrogel-released HATMSC2 supernatant were investigated in vitro by assessing the proliferation and metabolic activity of human fibroblast, endothelial cells and keratinocytes. Hydrogel degradation was measured using hydroxyproline assay while protein released from the hydrogel was assessed by interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) ELISAs. Pro-angiogenic activity of the developed treatment was assessed by tube formation assay while the presence of pro-angiogenic miRNAs in the HATMSC2 supernatant was investigated using real-time RT-PCR. The results demonstrated that the therapeutic effect of the HATMSC2-produced factors is maintained following incorporation into collagen hydrogel as confirmed by increased proliferation of skin-origin cells and improved angiogenic properties of endothelial cells. In addition, HATMSC2 supernatant revealed antimicrobial activity, and which therefore, in combination with the hydrogel has a potential to be used as advanced wound-healing dressing.

Preparation and characterization of novel anti-inflammatory biological agents based on piroxicam-loaded poly-ε-caprolactone nano-particles for sustained NSAID delivery

Piroxicam (PX), a main member of non-steroidal anti-inflammatory drugs (NSAIDs), is mainly used orally, which causes side effects of the gastrointestinal tract. It also has systemic effects when administered intramuscularly. Intra-articular (IA) delivery and encapsulation of PX in biodegradable poly-ε-caprolactone (PCL) nanoparticles (NPs) offer potential advantages over conventional oral delivery. The purpose of this study is the development of a new type of anti-inflammatory bio-agents containing collagen and PX-loaded NPs, as an example for an oral formulation replacement, for the prolonged release of PX. In this study, the PX was encapsulated in PCL NPs (size 102.7 ± 19.37 nm, encapsulation efficiency 92.83 ± 0.4410) by oil-in-water (o/w) emulsion solvent evaporation method. Nanoparticles were then characterized for entrapment efficiency, percent yield, particle size analysis, morphological characteristics, and in vitro drug release profiles. Eventually, the NPs synthesized with collagen were conjugated so that the NPs were trapped in the collagen sponges using a cross-linker. Finally, biocompatibility tests showed that the anti-inflammatory agents made in this study had no toxic effect on the cells. Based on the results, it appears that PX-loaded PCL NPs along with collagen (PPCLnp-Coll) can be promising for IA administration based on particulate drug delivery for the treatment of arthritis.

Evaluation of 1-Ethyl-3-(3-Dimethylaminopropyl) Carbodiimide Cross-Linked Collagen Membranes for Guided Bone Regeneration in Beagle Dogs

The purpose of this study was to evaluate the bone regeneration efficacy of an 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-cross-linked collagen membrane for guided bone regeneration (GBR). A non-cross-linked collagen membrane (Control group), and an EDC-cross-linked collagen membrane (Test group) were used in this study. In vitro, mechanical, and degradation testing and cell studies were performed. In the animal study, 36 artificial bone defects were formed in the mandibles of six beagles. Implants were inserted at the time of bone grafting, and membranes were assigned randomly. Eight weeks later, animals were sacrificed, micro-computed tomography was performed, and hematoxylin-eosin stained specimens were prepared. Physical properties (tensile strength and enzymatic degradation rate) were better in the Test group than in the Control group. No inflammation or membrane collapse was observed in either group, and bone volumes (%) in defects around implants were similar in the two groups (p > 0.05). The results of new bone areas (%) analysis also showed similar values in the two groups (p > 0.05). Therefore, it can be concluded that cross-linking the collagen membranes with EDC is the method of enhancing the physical properties (tensile strength and enzymatic degradation) of the collagen membranes without risk of toxicity.