12 research outputs found
Mesenchymal stem cell and gelatin microparticle encapsulation in thermally and chemically gelling injectable hydrogels for tissue engineering
In this work, we investigated the viability and osteogenic differentiation of mesenchymal stem cells encapsulated with gelatin microparticles (GMPs) in an injectable, chemically and thermally gelling hydrogel system combining poly(N-isopropylacrylamide)-based thermogelling macromers containing pendant epoxy rings with polyamidoamine-based hydrophilic and degradable diamine crosslinking macromers. Specifically, we studied how the parameters of GMP size and loading ratio affected the viability and differentiation of cells encapsulated within the hydrogel. We also examined the effects of cell and GMP co-encapsulation on hydrogel mineralization. Cells demonstrated long-term viability within the hydrogels, which was shown to depend on GMP size and loading ratio. In particular, increased interaction of cells and GMPs through greater available GMP surface area, use of an epoxy-based chemical gelation mechanism, and the tunable high water content of the thermogelled hydrogels led to favorable long-term cell viability. Compared with cellular hydrogels without GMPs, hydrogels co-encapsulating cells and GMPs demonstrated greater production of alkaline phosphatase by cells at all time-points and a transient early enhancement of hydrogel mineralization for larger GMPs at higher loading ratios. Such injectable, in situ forming hydrogels capable of delivering and maintaining populations of encapsulated mesenchymal stem cells and promoting mineralization in vitro offer promise as novel therapies for applications in tissue engineering and regenerative medicine
Synthesis and Characterization of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering
Novel, injectable hydrogels were developed that solidify through a dual-gelation, physical and
chemical, mechanism upon preparation and elevation of temperature to 37°C. A thermogelling,
poly(N-isopropylacrylamide)-based macromer with pendant epoxy rings and a hydrolyticallydegradable
polyamidoamine-based diamine crosslinker were synthesized, characterized, and
combined to produce in situ forming hydrogel constructs. Network formation through the epoxyamine
reaction was shown to be rapid and facile, and the progressive incorporation of the
hydrophilic polyamidoamine crosslinker into the hydrogel was shown to mitigate the often
problematic tendency of thermogelling materials to undergo significant post-formation gel
syneresis. The results suggest that this novel class of injectable hydrogels may be attractive
substrates for tissue engineering applications due to the synthetic versatility of the component
materials and beneficial hydrogel gelation kinetics and stability
Thiolated Thermoresponsive Polymer Scaffolds with Tunable Mucoadhesivity for Intestinal Applications
Perspectives on the Interface of Drug Delivery and Tissue Engineering
Controlled drug delivery of bioactive molecules continues to be an essential component of engineering strategies for tissue defect repair. This article surveys the current challenges associated with trying to regenerate complex tissues utilizing drug delivery and gives perspectives on the development of translational tissue engineering therapies which promote spatiotemporal cell-signaling cascades to maximize the rate and quality of repair
Structure-Property Evaluation of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering
The impact of synthesis and solution formulation parameters on the swelling and mechanical properties of a novel class of thermally and chemically gelling hydrogels combining poly(N-isopropylacrylamide)-based thermogelling macromers containing pendant epoxy rings with polyamidoamine-based hydrophilic and degradable diamine cross-linking macromers was evaluated. Through variation of network hydrophilicity and capacity for chain rearrangement, the often problematic tendency of thermogelling hydrogels to undergo significant syneresis was addressed. The demonstrated ability to tune postformation dimensional stability easily at both the synthesis and formulation stages represents a significant novel contribution toward efforts to utilize poly(N-isopropylacrylamide)-based polymers as injectable biomaterials. Furthermore, the cytocompatibility of the hydrogel system under relevant conditions was established while demonstrating time- and dose-dependent cytotoxicity at high solution osmolality. Such injectable in situ forming degradable hydrogels with tunable water content are promising candidates for many tissue-engineering applications, particularly for cell delivery to promote rapid tissue regeneration in non-load-bearing defects
Synthesis, Physicochemical Characterization, and Cytocompatibility of Bioresorbable, Dual-Gelling Injectable Hydrogels
Injectable, dual-gelling hydrogels
were successfully developed
through the combination of physical thermogellation at 37 °C
and favorable amine:epoxy chemical cross-linking. Poly(<i>N</i>-isopropylacrylamide)-based thermogelling macromers with a hydrolyzable
lactone ring and epoxy pendant groups and a biodegradable diamine-functionalized
polyamidoamine cross-linker were synthesized, characterized, and combined
to produce nonsyneresing and bioresorbable hydrogels. Differential
scanning calorimetry and oscillatory rheometry demonstrated the rapid
and dual-gelling nature of the hydrogel formation. The postgelation
dimensional stability, swelling, and mechanical behavior of the hydrogel
system were shown to be easily tuned in the synthesis and formulation
stages. The leachable products were found to be cytocompatible under
all conditions, while the degradation products demonstrated a dose-
and time-dependent response due to solution osmolality. Preliminary
encapsulation studies showed mesenchymal stem cell viability could
be maintained for 7 days. The results suggest that injectable and
thermally and chemically cross-linkable hydrogels are promising alternatives
to prefabricated biomaterials for tissue engineering applications,
particularly for cell delivery