title: Thermally labile components of aqueous humor potently induce osteogenic potential in adipose-derived mesenchymal stem cells.
abstract: Adipose-derived mesenchymal stem cells (ASCs) hold promise for use in cell-based therapies. Their intrinsic anti-inflammatory properties are potentially useful for treatments of inflammatory conditions such as uveitis, while their ability to differentiate along multiple cell lineages suggests use in regenerating damaged or degenerated tissue. However, how ASCs will respond to the intraocular environment is poorly studied. We have recently reported that aqueous humor (AH), the fluid that nourishes the anterior segment of the eye, potently increases alkaline phosphatase (ALP) activity of ASCs, indicating osteogenic differentiation. Here, we expand on our previous findings to better define the nature of this response. To this end, we cultured ASCs in the presence of 0, 5, 10, and 20% AH and assayed them for ALP activity. We found ALP activity correlates with increasing AH concentrations from 5 to 20%, and that longer treatments result in increased ALP activity. By using serum free media and pretreating AH with dextran-coated charcoal, we found that serum and charcoal-adsorbable AH components augment but are not required for this response. Further, by heat-treating the AH, we established that thermally labile components are required for the osteogenic response. Finally, we showed myocilin, a protein present in AH, could induce ALP activity in ASCs. However, this was to a lesser extent than untreated 5% AH, and myocilin could only partially rescue the effect after heat treatment, documenting there were additional thermally labile constituents of AH involved in the osteogenic response. Our work adds to the understanding of the induction of ALP in ASCs following exposure to AH, providing important insight in how ASCs will be influenced by the ocular environment. In conclusion, increased osteogenic potential upon exposure to AH represents a potential challenge to developing ASC cell-based therapies directed at the eye.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Morgan
authors.affiliation: Section of Retinal Ganglion Cell Biology, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, MD, USA.
authors.forename: Heung Sun
authors.initials: HS
authors.lastname: Kwon
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Wood
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Dori L
authors.initials: DL
authors.lastname: Borjesson
authors.affiliation: Section of Retinal Ganglion Cell Biology, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, MD, USA.
authors.forename: Stanislav I
authors.initials: SI
authors.lastname: Tomarev
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA; Department of Ophthalmology & Vision Science, School of Medicine, University of California, Davis, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murphy
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, USA. Electronic address: prussell@ucdavis.edu.
authors.forename: Paul
authors.initials: P
authors.lastname: Russell
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000704:Analysis of Variance; D001082:Aqueous Humor / Q000737:chemistry / Q000502:physiology*; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005136:Eye Proteins / Q000494:pharmacology; D006023:Glycoproteins / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000201:enzymology*; D010012:Osteogenesis / Q000502:physiology*; D000099179:Myocilin
chemical_list: D000469:Alkaline Phosphatase; D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins; D005136:Eye Proteins; D006023:Glycoproteins; D000099179:Myocilin
keywords: Alkaline phosphatase; Aqueous humor; Mesenchymal stem cells; Myocilin; Osteogenic potential