Rheological Studies of Injectable Thermoresponsive Biodegradable Hydrogels and Porcine Ocular Tissues
Date of Award
Master of Science (MS)
Tao L. Lowe, Ph.D.
David Hamilton, D.V.M. George Huang. D.Sc. Bernd Meibohm, Ph.D.
Hydrogels, Ocular Tissues, Rheology, Stem Cells, Thermoresponsive, Tissue Engineering
This research has evaluated the rheological properties of two types of materials which include (i) semi-synthetic polymer-based injectable hydrogels [P(NIPAAm-co-DEX-Lactate HEMA) and P(NIPAAm-co-HA-AEMA)], and (ii) biological tissues (porcine ocular tissues).
A series of thermoresponsive and biodegradable in situ hydrogel based on N-isopropyacrylamide (NIPAAm) monomer and hydrolytically degradable oligolactate Dextran-lactate-HEMA or Hyaluronic acid (HA)-AEMA macromer were investigated as encapsulation matrices (scaffolds) for DPSCs/ADSCs and assess their applicability in dental/retinal tissue engineering. The rheological properties of the hydrogels were strongly dependent on the reaction conditions and composition of the hydrogels. Both the hydrogels exhibited linear viscoelasticity, and the values of storage moludus (G´) at 1 Hz appeared in the range of 15-35 Pa for P(NIPAAm-co-DEX-Lactate HEMA) gels and 20-40 Pa for P(NIPAAm-co-HA-AEMA) gels at 15 mg·mL-1 concentration. No significant differences were found for the hydrogels prepared with the HA or dextran at the same concentration and monomer to macromer ratio (19:1). The hydrogels were nontoxic to DPSCs and ADSCs at a concentration up to 15 mg·mL-1, and in vitro survival studies using MTT and DAPI indicated that both DPSCs and ADSCs have favorably adhered and proliferated within the dextran and HA-based hydrogels. Survival of the DPSCs/ADSCs in the hydrogels, growth and morphology make these scaffolds a viable option for using as a biological scaffold for tissue engineering.
Since the functionality of the ocular tissues closely depends on their biomechanical properties, the rheological properties of the ocular tissues at different stages of development (preterm, neonatal and adult stage) is of therapeutic interest and has not been thoroughly investigated. This study has investigated the shear properties of porcine cornea, sclera and vitreous under strain and frequency sweep. All three tissue types at different stages have shown linear viscoelastic region under strain sweep. The G´ of cornea and vitreous weakly varied between neonatal and preterm, however, the adult cornea (~1.3-fold) and vitreous (~1.8-fold) showed significant higher moduli. On the other hand, the G´ of the sclera increased significantly with the developmental stage of the tissue, (preterm
Damera, Chandana Reddy (http://orcid.org/0000-0002-2768-1948), "Rheological Studies of Injectable Thermoresponsive Biodegradable Hydrogels and Porcine Ocular Tissues" (2018). Theses and Dissertations (ETD). Paper 456. http://dx.doi.org/10.21007/etd.cghs.2018.0448.