The Therapeutic Potential of Exogenous Adenosine Triphosphate (ATP) for Cartilage Tissue Engineering

Abstract

Objective:While mechanical stimuli can be used to enhance the properties of engineered cartilage, a promising alternative may be to directly harness the underlying mechanotransduction pathways responsible. Our initial studies on the adenosine triphosphate (ATP)–purinergic receptor pathway demonstrated that stimulation by exogenous ATP improved tissue growth and properties but elicited matrix turnover under high doses (250 µM) potentially due to the accumulation of extracellular inorganic pyrophosphate (ePPi). Therefore, the purpose of this study was to identify the mechanism of ATP-mediated catabolism and determine a therapeutic dose to maximize the anabolic effect.Design:Isolated bovine articular chondrocytes were seeded in high-density, 3-dimensional culture supplemented with varying doses of ATP for 4 weeks. The effects on biosynthesis, matrix metalloproteinase 13 (MMP-13) protein activity, and PPi accumulation were determined. Separate monolayer experiments were conducted to determine the effect of ePPi on MMP-13 activity.Results:High doses of ATP resulted in an increase in ePPi accumulation (by 54%) and MMP-13 activity (by 39%). Monolayer experiments confirmed a link between increased ePPi accumulation and MMP-13 activity, which appeared to require calcium and was inhibited by the MEK1/2 inhibitor U0126. Cultures supplemented with 62.5 to 125 µM ATP favored an anabolic response, which represented the therapeutic dose range.Conclusions:A therapeutic dose range of exogenous ATP to improve the properties of engineered cartilage has been identified, and a possible catabolic mechanism involving excess PPi was determined. Future research into PPi signal transduction and pathological crystal formation is necessary to maximize the beneficial effect of exogenous ATP on chondrocyte cultures.

Chondrogenic Differentiation of Human Mesenchymal Stem Cells Results in Substantial Changes of Ecto‐Nucleotides Metabolism

“…Rosenthal et al reported that P2 receptor agonists, such as ATP and ADP, increased PPi production and accumulation in vitro; whereas suramin, a P2 receptor antagonist, suppressed this increase. Moreover, the cultures of bovine articular chondrocytes supplemented with 62.5–250 μM ATP increased biosynthesis and accumulation of matrix components and exhibited the improved tissue growth and properties (Waldman et al, ; Usprech et al, ). Chondrocyte pellet cultures treated with ATP produced more proteoglycans and collagen that enhanced their functional properties (Croucher et al, ).…”

How to influence the mesenchymal stem cells fate? Emerging role of ectoenzymes metabolizing nucleotides

“…Rosenthal, Hempel, Kurup, Masuda, and Ryan () confirmed that the P2 receptor agonists such as ATP and ADP increased pyrophosphate production and accumulation in chondrocytes cultured in vitro. Moreover, the cultures of bovine articular chondrocytes supplemented with 62.5–250 µM ATP increased the biosynthesis and accumulation of matrix components, leading ultimately to an improved tissue growth and enhanced functional biomechanical properties of cartilage (Usprech, Chu, Giardini‐Rosa, Martin, & Waldman, ). Another set of results reveals that ATP inhibited cartilage formation in micromass cultures of chick limb undifferentiated mesenchymal cells; however, they stimulated cartilage proteoglycan and collagen accumulation in bovine chondrocyte pellet cultures (for an extensive review see Burnstock et al, ).…”

ATP promotes extracellular matrix biosynthesis of intervertebral disc cells

“…In the literature, the dose range of 62.5 – 125 µM ATP favored ECM production in articular chondrocytes in 3-dimensional agarose culture (Usprech, et al, 2012). Therefore, experimental groups included: Control (no ATP), 20 µM and 100 µM ATP treatment groups (NP: n = 9; AF: n = 9 for each group).…”