Journal of Bioactive and Compatible Polymers current issue

Heparinized Micropatterned Surfaces for the Spatial Control of Human Mesenchymal Stem Cells

Fri, 23 Oct 2009 04:11:33 PDT

In this study, a heparinized micropattern surface was prepared for the spatial control of human mesenchymal stem cells (hMSCs) that can differentiate into the desired tissues. Poly(styrene-co-vinylbenzyl N,N-diethyl-dithiocarbamate) (poly(ST-co-VBDC)) was synthesized as a photoreactive polymer; poly(ethylene glycol) methacrylate (PEGMA) was polymerized on the poly(ST-co-VBDC) coated surface by UV irradiation. XPS spectra revealed the residual DC moieties on the PEGMA-grafted surface and the linear chain growth of PEGMA was monitored according to irradiation time. After chemical immobilization of heparin onto this PEGMA surface, surface micropatterning was carried out by additional photopolymerization of PEGMA using a photomask. After incubation for 4 hour, the hMSCs adhered to the heparinized surface, while the hydrophilic PEGMA surface demonstrated no cell adhesion even after basic fibroblast growth factor (bFGF) treatment. Good alignment of hMSCs on the pattern-surface was distinctly observed along micron-sized grooves due to the presence of both heparin and bFGF. This heparinized micropattern surface can be used to study in vitro hMSCs responses with various heparin-binding growth factors in tissue engineering fields as well as cellular array for the spatial control of hMSCs.

Biomimetic Apatite-coated PCL Scaffolds: Effect of Surface Nanotopography on Cellular Functions

Beskardes, I. G., Gumusderelioglu, M. — Fri, 23 Oct 2009 04:11:33 PDT

In this study, polycaprolactone (PCL) scaffolds, consisting of agglomerated microspheres with nanotopographic surface structures, were fabricated by the freeze-drying method. These scaffolds were coated with bone-like apatite by using a calcium phosphate solution similar to saturated simulated body fluid (10x SBF-like) in two different immersion periods (6 and 24 h). Scanning electron microscopic views of the 6-h treatment in 10x SBF-like solution showed formation of calcium phosphate nucleation sites on the PCL scaffolds, while the apatite particles formed characteristic cauliflower-like morphology after 24 h. The X-ray diffraction (XRD) data showed that the mineral phase was made of hydroxyapatite (HA). The osteogenic activity of untreated and SBF-treated PCL scaffolds was examined by pre-osteoblastic MC3T3 cell culture studies. Cells had attached and spread on both the PCL scaffolds and the 6-h SBF immersion-treated scaffolds.

Hydrogels Based on Carboxymethylcellulose and Gelatin for Inclusion and Release of Chloramphenicol

Buhus, G., Popa, M., Desbrieres, J. — Fri, 23 Oct 2009 04:11:33 PDT

Hydrogels based on carboxymethylcellulose (CMC) and gelatin (GEL) crosslinked with glutaraldehyde were used to obtain interpenetrated— interconnecting polymer networks. They are designed to obtain controlled release polymeric drug systems. CMC and GEL were chosen for their biocompatibility and nontoxicity, which are compulsory conditions for polymers used in biomedical applications. By modifying the parameters of the crosslinking reaction, the obtained networks presented different crosslinking degrees and hence different swelling capacities. These properties determined the quantity of drug able to be loaded (0.25 g per gram of hydrogel). We obtained systems for which biologically active matter release was controlled by diffusion. The kinetics were zero-order during the major part of release period (~500 min). These systems improve the bactericide activity compared with free drugs.

Biodegradable Adhesives Composed of Human Serum Albumin and Organic Acid-based Crosslinkers with Active Ester Groups

Taguchi, T., Saito, H., Iwasashi, M., Sakane, M., Ochiai, N. — Fri, 23 Oct 2009 04:11:33 PDT

The organic acid-based crosslinkers trisuccinimidyl citrate (TSC), disuccinimidyl malate (DSM), and disuccinimidyl tartarate (DST) were combined with human serum albumin (HSA) to produce biodegradable solid— liquid-type adhesives, TSC-A, DSM-A, and DST-A. The bonding time of TSC-A, DSM-A, and DST-A was 15, 10, and 5 min, respectively, when the content of organic acid-based crosslinkers was 0.5 mmol and the HSA concentration was 44 w/v%. Five minutes after application of the adhesives, the DST-A adhesive had the greatest bonding strength (489.14 ± 93.06 kPa) compared with TSC-A (120.86 ± 73.83 kPa) and DSM-A (224.44 ± 79.53 kPa). The bonding strength of DSM-A and DST-A increased with increasing DSM or DST content up to 0.5 mmol, after that the bonding strength decreased. While, the bonding strength of the TSC-A adhesive was relatively low at any TSC content compared with the other adhesives. The bonding strength of DST-A with 0.3 mmol of DST increased with increasing HSA concentration up to 44 w/v%, and then decreased. The bonding strength of the DST-A adhesive was 3.2-fold greater than that of a commercial aldehyde-based adhesive and 6-fold greater than that of a fibrin-based adhesive. DST-A has excellent biocompatibility, bioabsorbability, and only mild tissue reaction in rat subcutaneous tissues.

Effects of Chitosan on Properties of Novel Human-like Collagen/Chitosan Hybrid Vascular Scaffold

Zhu, C., Fan, D., Ma, X., Xue, W., Yu, Y., Luo, Y., Liu, B., Chen, L. — Fri, 23 Oct 2009 04:11:33 PDT

Novel human-like collagen (HLC)/chitosan hybrid scaffolds were fabricated at blend ratios of 0%, 0.02%, 0.2% by crosslinking and freeze-drying process. The properties of the scaffolds were investigated, including morphology, mechanical strength, degradability, and cell biocompatibility. When the blend ratio was 0.02%, the morphology of the scaffolds was highly homogeneous with interconnected porous structure 46 ± 9 µm in size (SEM). The X-ray photoelectron spectroscopy analysis indicated intermolecular crosslinks between HLC and chitosan. The strain and stress of the scaffolds were 37.9 ± 3.3% and 309.7 ± 19.7 KPa, respectively. Human venous fibroblasts were expanded and seeded into the scaffolds in the density of 1 x 10⁵ cells/cm³ under static conditions. The cell morphology and proliferation were investigated using SEM, H&E, and MTT assay, which showed that the optimal content of the chitosan was signifcantly enhanced the cells adhesion, proliferation, and viability, compared to pure HLC, pure chitosan, and 0.2% chitosan/HLC scaffolds. These hybrid scaffolds appear to have favorable characteristics for vascular tissue engineering application.