title: Inorganic polyphosphates enhances nucleus pulposus tissue formation in vitro.
abstract: Disc degeneration is associated with low back pain for which currently there is no optimal therapy so there is a great need to identify new treatment approaches. Inorganic polyphosphates (polyP) are linear polymers of orthophosphate units varying in chain length and present in many cell types. As polyP has anabolic effects on chondrocytes, we hypothesized that polyP treatment would enhance matrix accumulation by nucleus pulposus (NP) cells. NP cells isolated from bovine caudal discs were grown in 3D culture under normoxic or in select experiments under hypoxic conditions, in the presence or absence of various concentrations and sizes of polyP. Gene expression was determined using RT-PCR. Matrix accumulation was quantified by measuring proteoglycan and collagen contents. DAPI fluorescence shift was used to stain for polyP in tissue. DAPI staining showed polyP present predominantly in the pericellular region of in vitro formed tissue. PolyP treatment enhanced matrix accumulation in a concentration and chain length dependant manner. NP cells exposed to polyP-22 (22 phosphate units length) showed an increase in gene expression of aggrecan, Collagen II, Sox 9, and MMP-13 which was maintained for the 14 days of culture. This suggests that polyP may enhance NP tissue formation in vitro by upregulating the expression of matrix genes. As polyP enhances proteoglycan accumulation even under hypoxic conditions, this raises the possibility that polyP may be a novel treatment to induce NP regeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:41-50, 2017.
authors.affiliation: Lunenfeld-Tanenbaum Research Institute, Mt Sinai Hospital, Toronto, Canada.|Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
authors.forename: Rahul
authors.initials: R
authors.lastname: Gawri
authors.affiliation: Regenetiss Inc., Kunitachi, Tokyo, Japan.|Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Shiba
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.|Faculty of Dentistry, University of Toronto, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Pilliar
authors.affiliation: Lunenfeld-Tanenbaum Research Institute, Mt Sinai Hospital, Toronto, Canada.|Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.|Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Suite 6-500, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: Rita
authors.initials: R
authors.lastname: Kandel
mesh_terms: D045930:Anabolic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D002417:Cattle; D004247:DNA / Q000378:metabolism; D004353:Drug Evaluation, Preclinical; D005109:Extracellular Matrix / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D000860:Hypoxia / Q000378:metabolism; D055959:Intervertebral Disc Degeneration / Q000188:drug therapy*; D000070614:Nucleus Pulposus / Q000187:drug effects* / Q000378:metabolism; D011122:Polyphosphates / Q000494:pharmacology / Q000627:therapeutic use*; D061251:Primary Cell Culture
chemical_list: D045930:Anabolic Agents; D011122:Polyphosphates; D004247:DNA
keywords: bioactive compounds; inorganic polyphosphates; intervertebral disc degeneration; regeneration; tissue engineering; biological repair