Characterization of a full-thickness decellularized and lyophilized human placental membrane for clinical applications.

Allografts derived from live-birth tissue obtained with donor consent have emerged as an important treatment option for wound and soft tissue repairs. Placental membrane derived from the amniotic sac consists of the amnion and chorion, the latter of which contains the trophoblast layer. For ease of cleaning and processing, these layers are often separated with or without re-lamination and the trophoblast layer is typically discarded, both of which can negatively affect the abundance of native biological factors and make the grafts difficult to handle. Thus, a full-thickness placental membrane that includes a fully-intact decellularized trophoblast layer was developed for homologous clinical use as a protective barrier and scaffold in soft tissue repairs. Here, we demonstrate that this full-thickness placental membrane is effectively decellularized while retaining native extracellular matrix (ECM) scaffold and biological factors, including the full trophoblast layer. Following processing, it is porous, biocompatible, supports cell proliferation in vitro, and retains its biomechanical strength and the ability to pass through a cannula without visible evidence of movement or damage. Finally, it was accepted as a natural scaffold in vivo with evidence of host-cell infiltration, angiogenesis, tissue remodelling, and structural layer retention for up to 10 weeks in a murine subcutaneous implant model.

Construction and antitumor properties of a targeted nano-drug carrier system responsive to the tumor microenvironment.

Doxorubicin (DOX) is one of the most commonly used and effective chemotherapy drugs among anthracyclines. An inherent limitation of DOX is its nonspecificity, which can cause serious side effects, thereby preventing the therapeutic use of high drug doses. In this study, we designed and created a simple nano-drug delivery system (PEG-MAF = P) with low biological toxicity that was responsive to the tumor environment. PEG-MAF = P was designed to self-assemble into nanospheres via control of a phenylalanine dipeptide (FF). The N-terminus of the peptide was linked to aldehyde groups at both ends of oxidized Pluronic F127 (F127-CHO) via Schiff bonds. The acidic environment surrounding the tumors was suitable for triggering the Schiff bonds, causing the nanospheres to disintegrate. The C-terminus of FF was connected to a ligand peptide, ATN-161, which was able to recognize cells expressing high levels of integrin α5ß1 antigens both in vivo and in vitro. To prevent the impediment in drug release, PEG was linked via a matrix metalloproteinase-9 response peptide. Therefore, in an acidic tumor microenvironment containing MMP-9, PEG-MAF = P disintegrated and rapidly released the drug. PEG-MAF = P exhibited low cytotoxicity, high drug-loading rate, and excellent antitumor properties both in vivo and in vitro. Compared with free DOX, PEG-MAF = P-DOX reduced injury to normal tissues.

Vasculature reconstruction of decellularized liver scaffolds via gelatin-based re-endothelialization.

Decellularized liver scaffolds based liver engineering is a promising approach toward developing functional liver surrogates. However, a major obstacle to long-term transplantation is the hemocompatibility of the bioengineered liver surrogates. One approach to improve the hemocompatibility of engineered liver surrogates is re-endothelialization. In the current study, immortalized endothelial cells were perfused for re-endothelialization of decellularized rat liver scaffolds. When compared to the media-based perfusion approach, gelatin hydrogels-based perfusion significantly increased the number of cells that were retained in the decellularized liver scaffolds and the vascular lumen coverage ratio. Endothelial cells were lining along the vasculatures of the decellularized liver scaffolds and actively proliferating. Re-endothelialization improved the blood retention ability of the liver scaffold vasculatures. Doppler ultrasound detected active blood flows within the re-endothelialized liver scaffold transplants 8 days post-transplantation. Our results strengthened the feasibility of developing bioengineered liver surrogates utilizing decellularized liver scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 392-402, 2019.

Self-assembled copper-capillary alginate gel scaffolds with oligochitosan support embryonic stem cell growth.

Biomaterial scaffolds are fundamental components of strategies aimed at engineering a wide range of tissues. Scaffolds possessing uniform, oriented microtubular architectures could be ideal for multiple tissues, but are challenging to produce. Therefore, we developed hydrogel scaffolds possessing regular, tubular microstructures from self-assembled copper-capillary alginate gel (CCAG). To abrogate the rapid dissolution of CCAG in cell culture media, we treated it with oligochitosan and created a stable oligochitosan-CCAG (OCCAG) polyelectrolyte complex. Fourier transform infrared spectroscopy confirmed polyelectrolyte complexation between alginate and oligochitosan. OCCAG retained capillary morphology, shrank anisotropically in bulk, lost Cu(2+) ions, and maintained (71.9 +/- 5.65)% of its mass in cell culture media. Next, we seeded mouse embryonic stem (ES) cells within OCCAG scaffolds, and examined cell morphology and quantified cell growth and viability over four days. ES cells were guided to form cylindrical structures of staggered cells within scaffold capillaries. Analysis of the total cells recovered from the scaffolds revealed exponential cell growth (normalized to day 0) that was statistically similar to gelatinized-plate controls. OCCAG-cultured ES cell viability was also not significantly different from controls at day 4. CCAG-derived scaffolds can therefore serve as a unique platform for stem cell-based tissue engineering.

Inducing alignment in astrocyte tissue constructs by surface ligands patterned on biomaterials.

Planar substrates with patterned ligands were used to induce astrocyte alignment whereas substrates with uniform fields of ligand were used to produce random cell orientation. DRG neurons plated on top of oriented astrocyte monolayers exhibited directional outgrowth along aligned astrocytes, demonstrating that purely biological cues provided by the oriented astrocytes were sufficient to provide guidance cues. Antibody blocking studies demonstrated that astrocyte associated FN played a major mechanistic role in directing engineered neurite extension. Our results show that nanometer level surface cues are sufficient to direct nerve outgrowth through an intervening organized astrocyte cell layer. In other studies, we showed that patterned ligands were able to transmit organization cues through multiple cell layers to control the overall alignment of an astrocyte tissue construct, demonstrating how natural scar tissue may develop in situ into potent barriers. In such constructs the spatial organization of astrocyte derived FN maintained its organizational anisotropy throughout the thickness of multilayered astrocyte constructs. These in vitro studies suggest possible roles for such constructs as bridging substrates for neuroregenerative applications.

Sorption enhancement of aromatic sulfonates onto an aminated hyper-cross-linked polymer.

A macroreticular resin adsorbent CHA-101 was aminated by dimethylamine, and a novel sorbent named M-101 was obtained. Several industrially important aromatic sulfonates including sodium benzenesulfonate (BS), sodium p-toluenesulfonate (TS), and sodium 2-naphthalenesulfonate (NS) were selected as general solutes to evaluate the performance of the newly synthesized resin particles. X-ray photoelectron spectroscope (XPS) analyses was used to determine the protonation degree of amino group at different solution pH, and the effect of pH on the sorption of these solutes onto M-101 can be explained by the ion exchange mechanism. The experimentally observed sequence of the sorption capacity of the tested organic sulfonates onto M-101 indicates that the pi-pi interaction between the solute molecule and the polymer matrix plays an important role in uptake of organic sulfonates from aqueous solution. Sodium sulfate was selected as a typical competitive inorganic anion, and improved selectivity of BS sorption over sulfate on M-101 was observed by comparison with a common macroporous weak base anion exchanger D-301. In addition, both sorption and desorption kinetics of M-101 were also found to be faster than that of D-301. Analyses of sorption isotherms and thermodynamics proved that BS sorption on M-101 was an exothermic and more selective process than on D-301. Both column tests and field applications proved M-101 to be an effective sorbent that can be used to remove aromatic sulfonates from aqueous solution.