Biomedical subjects

Brenda K Mann

Publications and source records attributed to Brenda K Mann.

4 recordsLinked to original sources

PubMed2006

Stereolithography of three-dimensional bioactive poly(ethylene glycol) constructs with encapsulated cells.

Stereolithography (SL) was used to fabricate complex 3-D poly(ethylene glycol) (PEG) hydrogels. Photopolymerization experiments were performed to characterize the solutions for use in SL, where the crosslinked depth (or hydrogel thickness) was measured at different laser energies and photoinitiator (PI) concentrations for two concentrations of PEG-dimethacrylate in solution (20% and 30% (w/v)). Hydrogel thickness was a strong function of PEG concentration, PI type and concentration, and energy dosage, and these results were utilized to successfully fabricate complex hydrogel structures using SL, including structures with internal channels of various orientations and multi-material structures. Additionally, human dermal fibroblasts were encapsulated in bioactive PEG photocrosslinked in SL. Cell viability was at least 87% at 2 and 24 h following fabrication. The results presented here indicate that the use of SL and photocrosslinkable biomaterials, such as photocrosslinkable PEG, appears feasible for fabricating complex bioactive scaffolds with living cells for a variety of important tissue engineering applications.

Cell Culture Techniques↗

PubMed2005

Adhesive and mechanical properties of hydrogels influence neurite extension.

Photopolymerizable polyethylene glycol (PEG) hydrogels conjugated with bioactive ligands were examined for their use as scaffolds in peripheral nerve regeneration applications. The bioactivity and mechanical properties of PEG hydrogels can be tailored through the integration of bioactive factors (adhesion ligands, proteolytic sites, growth factors) and the alteration of PEG concentrations, respectively. For peripheral nerve regeneration, it will be important to determine the type and concentration of the bioactive molecules required to improve neurite extension. In this study, cell adhesion ligands (RGDS, IKVAV, and YIGSR) were covalently attached to PEG hydrogels. Both the type and concentration of cell adhesion ligand used affected neurite extension. Extension from PC12 cells was greater on hydrogels with RGDS incorporated than IKVAV, and the optimal concentration for each ligand was different. Cells adhered to but did not extend neurites on hydrogels with YIGSR. Cells did not adhere to hydrogels containing RGES. Furthermore, different combinations of these ligands affected neurite extension to different degrees. The mechanical properties of the hydrogels also significantly affected neurite extension. PC12 cells grown on more flexible hydrogels exhibited the greatest degree of neurite extension. PEG hydrogels have thus been developed with varying biochemical and mechanical properties that may enhance nerve regeneration.

Adhesiveness↗

PubMed2003

Biologic gels in tissue engineering.

There are many different types of scaffold materials now available for tissue engineering applications. Hydrogels form one group of materials that have been used in a wide variety of applications. These hydrogels can be formed using natural materials, synthetic materials, or some combination of the two. There are advantages and disadvantages to using each type of material, and detailed investigations into the effects on various aspects of cell behavior of chemical and physical properties of the materials are needed to make an informed decision as to which material is best suited for a given application. By combining appropriate scaffold materials, such as hydrogels, with cells and proper signaling for those cells, more commercial tissue engineering products will become available for general use.

Biocompatible Materials↗

PubMed2002

Cell adhesion peptides alter smooth muscle cell adhesion, proliferation, migration, and matrix protein synthesis on modified surfaces and in polymer scaffolds.

The effects of cell adhesion peptides (RGDS, KQAGDV, VAPG) on vascular smooth muscle cells grown on modified surfaces and in tissue-engineering scaffolds were examined. Cells were more strongly adhered to surfaces modified with adhesive ligands than to control surfaces (no ligand or a nonadhesive ligand). Cell migration was higher on surfaces with 0.2 nmol/cm(2) of adhesive ligand than on control surfaces, but it was lower on surfaces with 2.0 nmol/cm(2) of adhesive ligand than it was on control surfaces. Further, cell proliferation was lower on adhesive surfaces than it was on control surfaces, and it decreased as the ligand density increased. Similarly, in the peptide-grafted hydrogel scaffolds, cell proliferation was lower in scaffolds containing the adhesive peptides than it was in control scaffolds. After 7 days of culture, more collagen per cell was produced in control scaffolds than in scaffolds containing adhesive peptides. In addition, collagen production decreased in the scaffolds as the ligand concentration increased. While modification of a surface or scaffold material with adhesive ligands initially increases cell attachment, it may be necessary to optimize cell adhesion simultaneously with proliferation, migration, and matrix production.

Animals↗