title: Encapsulation and 3D culture of human adipose-derived stem cells in an in-situ crosslinked hybrid hydrogel composed of PEG-based hyperbranched copolymer and hyaluronic acid.
abstract: BACKGROUND
  Cell therapy using adipose-derived stem cells has been reported to improve chronic wounds via differentiation and paracrine effects. One such strategy is to deliver stem cells in hydrogels, which are studied increasingly as cell delivery vehicles for therapeutic healing and inducing tissue regeneration. This study aimed to determine the behaviour of encapsulated adipose-derived stem cells and identify the secretion profile of suitable growth factors for wound healing in a newly developed thermoresponsive PEG-hyaluronic acid (HA) hybrid hydrogel to provide a novel living dressing system.
  
  
  METHODS
  In this study, human adipose-derived stem cells (hADSCs) were encapsulated in situ in a water-soluble, thermoresponsive hyperbranched PEG-based copolymer (PEGMEMA-MEO2MA-PEGDA) with multiple acrylate functional groups in combination with thiolated HA, which was developed via deactivated enhanced atom transfer radical polymerisation of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, Mn = 475), 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and poly(ethylene glycol) diacrylate PEGDA (Mn = 258). hADSCs embedded in the PEGMEMA-MEO2MA-PEGDA and HA hybrid hydrogel system (P-SH-HA) were monitored and analysed for their cell viability, cell proliferation and secretion of growth factors (vascular endothelial growth factor, transforming growth factor beta and placental-derived growth factor) and cytokines (IFNγ, IL-2 and IL-10) under three-dimensional culture conditions via the ATP activity assay, alamarBlue® assay, LIVE/DEAD® assay and multiplex ELISA, respectively.
  
  
  RESULTS
  hADSCs were successfully encapsulated in situ with high cell viability for up to 7 days in hydrogels. Although cellular proliferation was inhibited, cellular secretion of growth factors such as vascular endothelial growth factor and placental-derived growth factor production increased over 7 days, whereas IL-2 and IFNγ release were unaffected.
  
  
  CONCLUSIONS
  This study indicates that hADSCs can be maintained in a P-SH-HA hydrogel, and secrete pro-angiogenic growth factors with low cytotoxicity. With the potential to add more functionality for further structural modifications, this stem cell hydrogel system can be an ideal living dressing system for wound healing applications.
authors.forename: Waqar
authors.initials: W
authors.lastname: Hassan
authors.forename: Yixiao
authors.initials: Y
authors.lastname: Dong
authors.forename: Wenxin
authors.initials: W
authors.lastname: Wang
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000295:instrumentation / Q000379:methods*; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry* / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008689:Methacrylates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; D016207:Cytokines; D036341:Intercellular Signaling Peptides and Proteins; D008689:Methacrylates; D011108:Polymers; C437167:poly(ethylene glycol)diacrylate; C524499:polyethylene glycol methacrylate; C539356:2-(2-methoxyethoxy)ethyl methacrylate; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; D006820:Hyaluronic Acid