title: A methylcellulose and collagen based temperature responsive hydrogel promotes encapsulated stem cell viability and proliferation in vitro.
abstract: With the number of stem cell-based therapies emerging on the increase, the need for novel and efficient delivery technologies to enable therapies to remain in damaged tissue and exert their therapeutic benefit for extended periods, has become a key requirement for their translation. Hydrogels, and in particular, thermoresponsive hydrogels, have the potential to act as such delivery systems. Thermoresponsive hydrogels, which are polymer solutions that transform into a gel upon a temperature increase, have a number of applications in the biomedical field due to their tendency to maintain a liquid state at room temperature, thereby enabling minimally invasive administration and a subsequent ability to form a robust gel upon heating to physiological temperature. However, various hurdles must be overcome to increase the clinical translation of hydrogels as a stem cell delivery system, with barriers including their low tensile strength and their inadequate support of cell viability and attachment. In order to address these issues, a methylcellulose based hydrogel was formulated in combination with collagen and beta glycerophosphate, and key development issues such as injectability and sterilisation processes were examined. The polymer solution underwent thermogelation at ~36 °C as determined by rheological analysis, and when gelled, was sufficiently robust to resist significant disintegration in the presence of phosphate buffered saline (PBS) while concomitantly allowing for diffusion of methylene blue dye solution into the gel. We demonstrate that human mesenchymal stem cells (hMSCs) encapsulated within the gel remained viable and showed raised levels of dsDNA at increasing time points, an indication of cell proliferation. Mechanical testing showed the "injectability", i.e. force required for delivery of the polymer solution through devices such as a syringe, needle or catheter. Sterilisation of the freeze-dried polymer wafer via gamma irradiation showed no adverse effects on the formed hydrogel characteristics. Taken together, these results indicate the potential of this gel as a clinically translatable delivery system for stem cells and therapeutic molecules in vivo.
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.|Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.
authors.forename: Christina
authors.initials: C
authors.lastname: Payne
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.|Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.
authors.forename: Eimear B
authors.initials: EB
authors.lastname: Dolan
authors.affiliation: Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.
authors.forename: Janice
authors.initials: J
authors.lastname: O'Sullivan
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.|Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland.|Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland.|Centre for Research in Medical Devices (CÚRAM), National University of Ireland Galway, Galway, Ireland.
authors.forename: Sally-Ann
authors.initials: SA
authors.lastname: Cryan
authors.affiliation: School of Pharmacy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland. helenakelly@rcsi.ie.|Tissue Engineering Research Group, Department of Anatomy, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland. helenakelly@rcsi.ie.
authors.forename: Helena M
authors.initials: HM
authors.lastname: Kelly
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000008:administration & dosage* / Q000737:chemistry; D005994:Glycerophosphates / Q000008:administration & dosage* / Q000737:chemistry; D006801:Humans; D020100:Hydrogels / Q000008:administration & dosage* / Q000737:chemistry; D059630:Mesenchymal Stem Cells / Q000187:drug effects*; D008747:Methylcellulose / Q000008:administration & dosage* / Q000737:chemistry; D012212:Rheology; D013696:Temperature
chemical_list: D005994:Glycerophosphates; D020100:Hydrogels; D008747:Methylcellulose; D003094:Collagen; C031463:beta-glycerophosphoric acid
keywords: Collagen; Gamma irradiation; Hydrogel; Injectability; Mesenchymal stem cells; Methylcellulose; Thermoresponsive