Evaluation of optical coherence tomography for the measurement of the effects of activators and anticoagulants on the blood coagulation in vitro

Abstract

Optical properties of human blood during coagulation were studied using optical coherence tomography (OCT) and the parameter of clotting time derived from the 1/e light penetration depth (d(1/e)) versus time was developed in our previous work. In this study, in order to know if a new OCT test can characterize the blood-coagulation process under different treatments in vitro, the effects of two different activators (calcium ions and thrombin) and anticoagulants, i.e., acetylsalicylic acid (ASA, a well-known drug aspirin) and melagatran (a direct thrombin inhibitor), at various concentrations are evaluated. A swept-source OCT system with a 1300 nm center wavelength is used for detecting the blood-coagulation process in vitro under a static condition. A dynamic study of d1/e reveals a typical behavior due to coagulation induced by both calcium ions and thrombin, and the clotting time is concentration-dependent. Dose-dependent ASA and melagatran prolong the clotting times. ASA and melagatran have different effects on blood coagulation. As expected, melagatran is much more effective than ASA in anticoagulation by the OCT measurements. The OCT assay appears to be a simple method for the measurement of blood coagulation to assess the effects of activators and anticoagulants, which can be used for activator and anticoagulant screening.

Fig. 1

OCT data processing of: (a) OCT image of a blood sample and (b) the curve fit for 1/e light penetration depth extraction.

Fig. 2

d_1/e as a function of time obtained from coagulating blood samples induced by 12, 18, and 25 mmol/L calcium chloride, including the samples without calcium ions (n = 3). The clotting time t_c is indicated by an arrow symbol. The clotting time was decreased with the increase of calcium concentration. Measuring points were taken every 20 s up to 15 min and every 1 min from 15 to 40 min.

Fig. 3

Time-course changes in d_1/e of the blood samples induced by 0.25, 0.5, 1, and 2 IU/mL thrombin, including the samples without thrombin (n = 3). The clotting time t_c is indicated by an arrow symbol. The clotting time was decreased by the increasing amount of thrombin.

Fig. 4

Dynamic d_1/e of the coagulating blood samples induced by 25 mmol/L calcium chloride with addition of ASA at concentrations of 0, 50, 100, 200, and 300 µmol/L (n = 3). The clotting time was prolonged with the increase of ASA concentration.

Fig. 5

Summary of clotting time of the blood samples with different (a) ASA and (b) melagatran (n = 3). ASA and melagatran had different effects on blood coagulation.

Fig. 6

Time-course changes in d_1/e of the blood samples induced by 25 mmol/L calcium chloride with addition of melagatran at concentrations of 0, 0.05, 0.1, 0.2, and 0.4 µmol/L (n = 3). The clotting time was prolonged with the increasing amount of melagatran.