title: Cell encapsulation and cryostorage in PVA-gelatin cryogels: incorporation of carboxylated ε-poly-L-lysine as cryoprotectant.
abstract: It is desirable to produce cryopreservable cell-laden tissue-engineering scaffolds whose final properties can be adjusted during the thawing process immediately prior to use. Polyvinyl alcohol (PVA)-based solutions provide platforms in which cryoprotected cell suspensions can be turned into a ready-to-use, cell-laden scaffold by a process of cryogelation. In this study, such a PVA system, with DMSO as the cryoprotectant, was successfully developed. Vascular smooth muscle cell (vSMC)-encapsulated cryogels were investigated under conditions of cyclic strain and in co-culture with vascular endothelial cells to mimic the environment these cells experience in vivo in a vascular tissue-engineering setting. In view of the cytotoxicity DMSO imposes with respect to the production procedure, carboxylated poly-L-lysine (COOH-PLL) was substituted as a non-cytotoxic cryoprotectant to allow longer, slower thawing periods to generate more stable cryogels. Encapsulated vSMC with DMSO as a cryoprotectant responded to 10% cyclic strain with increased alignment and proliferation. Cells were stored frozen for 1 month without loss of viability compared to immediate thawing. SMC-encapsulated cryogels also successfully supported functional endothelial cell co-culture. Substitution of COOH-PLL in place of DMSO resulted in a significant increase in cell viability in encapsulated cryogels for a range of thawing periods. We conclude that incorporation of COOH-PLL during cryogelation preserved cell functionality while retaining fundamental cryogel physical properties, thereby making it a promising platform for tissue-engineering scaffolds, particularly for vascular tissue engineering, or cell preservation within microgels.
authors.affiliation: Materials Processing Research Centre, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: Nihal E
authors.initials: NE
authors.lastname: Vrana
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Matsumura
authors.forename: Suong-Hyu
authors.initials: SH
authors.lastname: Hyon
authors.forename: Luke M
authors.initials: LM
authors.lastname: Geever
authors.forename: James E
authors.initials: JE
authors.lastname: Kennedy
authors.forename: John G
authors.initials: JG
authors.lastname: Lyons
authors.forename: Clement L
authors.initials: CL
authors.lastname: Higginbotham
authors.forename: Paul A
authors.initials: PA
authors.lastname: Cahill
authors.forename: Garrett B
authors.initials: GB
authors.lastname: McGuinness
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D002152:Calorimetry, Differential Scanning; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018914:Cells, Immobilized / Q000166:cytology / Q000187:drug effects; D018920:Coculture Techniques; D059985:Cryogels / Q000494:pharmacology*; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects; D005780:Gelatin / Q000494:pharmacology*; D008422:Materials Testing; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D011107:Polylysine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D011142:Polyvinyl Alcohol / Q000494:pharmacology*; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000187:drug effects
chemical_list: D059985:Cryogels; D003451:Cryoprotective Agents; D011107:Polylysine; D005780:Gelatin; D011142:Polyvinyl Alcohol