Tranexamic acid toxicity in human periarticular tissues

Abstract

Objectives: Tranexamic acid (TXA) is an anti-fibrinolytic medication commonly used to reduce perioperative bleeding. Increasingly, topical administration as an intra-articular injection or perioperative wash is being administered during surgery. Adult soft tissues have a poor regenerative capacity and therefore damage to these tissues can be harmful to the patient. This study investigated the effects of TXA on human periarticular tissues and primary cell cultures using clinically relevant concentrations.

Methods: Tendon, synovium, and cartilage obtained from routine orthopaedic surgeries were used for ex vivo and in vitro studies using various concentrations of TXA. The in vitro effect of TXA on primary cultured tenocytes, fibroblast-like synoviocytes, and chondrocytes was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assays, fluorescent microscopy, and multi-protein apoptotic arrays for cell death.

Results: There was a significant (p < 0.01) increase in cell death within all tissue explants treated with 100 mg/ml TXA. MTT assays revealed a significant (p < 0.05) decrease in cell viability in all tissues following treatment with 50 mg/ml or 100 mg/ml of TXA within four hours. There was a significant (p < 0.05) increase in cell apoptosis after one hour of exposure to TXA (100 mg/ml) in all tissues.

Conclusion: The current study demonstrates that TXA caused significant periarticular tissue toxicity ex vivo and in vitro at commonly used clinical concentrations.Cite this article: M. McLean, K. McCall, I. D. M. Smith, M. Blyth, S. M. Kitson, L. A. N. Crowe, W. J. Leach, B. P. Rooney, S. J. Spencer, M. Mullen, J. L. Campton, I. B. McInnes, M. Akbar, N. L. Millar. Tranexamic acid toxicity in human periarticular tissues. Bone Joint Res 2019;8:11-18. DOI: 10.1302/2046-3758.81.BJR-2018-0181.R1.

Keywords: Apoptosis; Cartilage; Periarticular tissues; Synovium; Tendon; Tranexamic acid.

Tranexamic acid (TXA) toxicity in periarticular tissues ex vivo. a) Percentage of dead cells in control (0 mg/ml) and TXA-treated (100 mg/ml) cells in each periarticular tissue (n = 3 tendon, synovium; n = 4 cartilage) after 16 hours of treatment. Mean ± standard error of the mean; Student’s paired t-test. †p < 0.01. b) Tendon, synovium, ligament, and cartilage tissue imaged by confocal microscopy with 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI) stain at 16 hours of treatment in control and TXA-treated (100 mg/ml TXA cells). Green stained cells counted as live and red stained cells counted as dead.

Tranexamic acid (TXA) toxicity in vitro. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of: a) to c) tenocyte (n = 11); d) to f) fibroblast-like synoviocyte (FLS; n = 5); and g) to i) chondrocyte (n = 5) viability at: a), d), g) one; b), e), h) four; and c), f), i) 24 hours. Values were measured as luminescence and expressed as percentage change from untreated (control) wells. *p < 0.05; †p < 0.01; ‡p < 0.001. Data are means ± standard error of the mean; one-way analysis of variance; Dunnett’s Multiple Comparison Test.

Tranexamic acid (TXA)-associated periarticular apoptosis. Percentage of: a) and b) tenocyte (n = 3); c) and d) fibroblast-like synoviocyte (FLS; n = 3); and e) and f) chondrocyte (n = 4) death at a), c), e) one and b), d), f) four hours with 0 mg/ml, 1 mg/ml, 50 mg/ml, or 100 mg/ml TXA treatment. Dying cells (green) were calculated as a proportion of healthy (red) cells. *p < 0.05; †p < 0.01. Data represent mean ± standard error of the mean; one-way analysis of variance; Dunnett’s Multiple Comparison Test. g) Fluorescent microscopy images show tenocytes, FLS, and chondrocytes at: one hour, 0 mg/ml TXA; one hour, 100 mg/ml TXA; and four hours, 100 mg/ml TXA.

a) Tranexamic acid (TXA)-associated periarticular apoptosis pathways. Caspase-3 activation induced by tranexamic acid in vitro in periarticular tissues: b) and c) tenocyte; d) and e) fibroblast-like synoviocyte (FLS); and f) and g) chondrocyte single-sample multi-protein apoptotic arrays. b), d), f) Pro caspase-3 and c), e), g) cleaved caspase-3 samples were treated with 0 mg/ml, 1 mg/ml, 50 mg/ml, or 100 mg/ml of TXA for one hour. Pro and cleaved forms of caspase-3 signal pixel density plotted relative to control spots. HSP, heat shock protein; XIAP, X-linked inhibitor of apoptosis protein; cIAP, cellular inhibitor of apoptosis protein; HO-1, heme oxygenase 1; HIF1-α, hypoxia-inducible factor 1-alpha.