![Figure 6. Fibrinolysis regulates the retraction and elastic modulus of fibrin clots formed in human PRP in vitro. (A) Fibrin clot retraction in vitro was examined using human PRP, as described in “Methods.” The various inhibitors were preincubated with PRP prior to clot formation. Clot retraction was quantified by measuring the volume of extruded serum 45 minutes after clot initiation and data expressed as a percentage (see “Methods”). Results depict the mean ± SEM (saline control, n = 17; TXA, n = 7; TAFI, n = 4; anti-plasmin, n = 3; anti-tPA immunoglobulin G [IgG] 1, n = 6; anti-tPA IgG 2, n = 3; FXIIIa inhibitor groups, n = 5); **P < .05, ***P < .001, and ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “saline control” group. (Insets) Representative photographs after 45 minutes of incubation. (B-C) Oscillation rheometry was used to measure the change in PRP clot elastic modulus following initiation of clot formation (as described in “Methods”), in the absence or presence of the indicated inhibitors, prior to clot initiation. (B) The histogram depicts relative maximal PRP elastic modulus, with data expressed as a percentage as described in “Methods.” Results represent the mean ± SEM (control, n = 8; TXA, n = 5; tPA-blocking IgG 1, n = 5; tPA-blocking IgG 2, n = 4; FXIIIa inhibitor, n = 7); ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “control” group. (C) The line graphs depict nonnormalized data from the experiments presented in panel B. A normalized summary of this same data is presented in supplemental Figure 6A. Results are depicted as elastic modulus (Pa) vs time (mean ± SEM). (D) The effect of different concentrations of exogenous rtPA on fibrin clot retraction in vitro was examined using human PRP, as described in panel A and “Methods.” Clot retraction was quantified by measuring the volume of extruded serum 45 minutes after clot initiation and data expressed as a percentage (see “Methods”). Results depict the mean + SEM (0.5 nM rtPA, n = 8; 5 nM rtPA, n = 4). ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “saline control” group. Insets, Representative photographs after 45 minutes of incubation. α2-AP, α2-antiplasmin; N/A, not applicable.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/130/23/10.1182_blood-2017-06-789032/4/blood789032f6.jpeg?Expires=1722729914&Signature=Ms~D0IK2lz6FObjCt5EhnG61rfa1dpLUnrqjz4v9edXplnj8~~08ZEKtQxwK4xHSkZdfET3j0FR5ROVf1g4OMb5jjqw67nD1Shmo1WxWdnySG3X0RnLpT4duOKLSdBYFJO3JIle~xBhJLuGpiLuGUWwupAiuPixkgyOdxgTn5VrRAgo654HdaFBCB2HvmhZ~N2FPRqQfDxB3v0IyWqPWkoMFP7OfqOV10cpZ66DXm60M7BHabD1Mp5nkUo5gzU3Q5tBiupa0T3Ru4rQj0Ru43eFg5pS4VgqImbAM2HdQoXrX8l1t-bq95xKO1zJpnmncfupXhOxVUf2oSwfCbA3bbA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Fibrinolysis regulates the retraction and elastic modulus of fibrin clots formed in human PRP in vitro. (A) Fibrin clot retraction in vitro was examined using human PRP, as described in “Methods.” The various inhibitors were preincubated with PRP prior to clot formation. Clot retraction was quantified by measuring the volume of extruded serum 45 minutes after clot initiation and data expressed as a percentage (see “Methods”). Results depict the mean ± SEM (saline control, n = 17; TXA, n = 7; TAFI, n = 4; anti-plasmin, n = 3; anti-tPA immunoglobulin G [IgG] 1, n = 6; anti-tPA IgG 2, n = 3; FXIIIa inhibitor groups, n = 5); **P < .05, ***P < .001, and ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “saline control” group. (Insets) Representative photographs after 45 minutes of incubation. (B-C) Oscillation rheometry was used to measure the change in PRP clot elastic modulus following initiation of clot formation (as described in “Methods”), in the absence or presence of the indicated inhibitors, prior to clot initiation. (B) The histogram depicts relative maximal PRP elastic modulus, with data expressed as a percentage as described in “Methods.” Results represent the mean ± SEM (control, n = 8; TXA, n = 5; tPA-blocking IgG 1, n = 5; tPA-blocking IgG 2, n = 4; FXIIIa inhibitor, n = 7); ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “control” group. (C) The line graphs depict nonnormalized data from the experiments presented in panel B. A normalized summary of this same data is presented in supplemental Figure 6A. Results are depicted as elastic modulus (Pa) vs time (mean ± SEM). (D) The effect of different concentrations of exogenous rtPA on fibrin clot retraction in vitro was examined using human PRP, as described in panel A and “Methods.” Clot retraction was quantified by measuring the volume of extruded serum 45 minutes after clot initiation and data expressed as a percentage (see “Methods”). Results depict the mean + SEM (0.5 nM rtPA, n = 8; 5 nM rtPA, n = 4). ****P < .0001 by 1-way ANOVA with Dunnett correction relative to “saline control” group. Insets, Representative photographs after 45 minutes of incubation. α2-AP, α2-antiplasmin; N/A, not applicable.
