Fig. 8.
Cell viability, hemocompatibility, and in vivo analysis. a Acute and b prolonged cytotoxicity of KLDLCyclic, KFDFCyclic, KLDLLinear, and KFDFLinear in human cardiac progenitor cells (CPCs). a Percent cell viability after peptide (10 mM) incubation for 4 h (n = 8–12 repeats in duplicate). b Fold increase (I/Io) over baseline of CPC viability after incubation for 24 and 48 h with 0, 50, 100, 250, 500, and 1000 µM peptide (n = 3 repeats in quadruplicate). c–f Hemocompatibility of progelator (shades of green, 1:20,000, 1:10,000, 1:5000, 1:1000, 1:500, 1:100, and 1:10 blood volume dilution of injected dosage) in human blood with positive (collagen, glass coverslip, and 1% Triton X-100), negative (no calcium), and vehicle (1× Dulbecco's phosphate-buffered saline (DPBS)) controls (blue, gray, and black, respectively). c Activated clotting times (ACT). No calcium controls are >1500 s (n = 6 per group). d Whole blood hemostasis kinetics at 5, 15, 30, and 45 min (n = 3 per group). e Hemolysis of red blood cells (RBCs) after 1 h of incubation (n = 4 per group). f Pro-thrombotic profiles in platelet-poor plasma (PPP). Onset of coagulation is accompanied by an increase in absorbance (n = 6 per group). g In vivo study timeline. Female Sprague-Dawley rats received ischemic reperfusion surgery (35 min occlusion), then a single 75 µL intramyocardial injection (10 mM peptide in 1× DPBS, pH 7.4) of KFDFCyclic (5 mol% Rho-KFDFCyclic) at 7 days post myocardial infarction (MI) to simulate a local injection. Animals were euthanized at 24 h post injection, and hearts were collected (n = 5 animals). Clipart adapted from Servier’s Medical Art database (https://smart.servier.com). h Hematoxylin and eosin (H&E)-stained representative heart section. Inset images illustrate hydrogel assembly in the infarct. Arrows show peptide material. i Corresponding fluorescence images of the neighboring section, stained for nuclei (blue) and α-actinin (green), with rhodamine-labeled peptide gels in red. LV left ventricle. Scale bars are 1 mm (h, i, inset 1) and 100 µm (inset 2), respectively. ns (p > 0.05), *p ≤ 0.05, ***p ≤ 0.001, and ****p ≤ 0.0001. Ordinary one-way analysis of variance (ANOVA) (c, e) and two-way ANOVA (d) for comparison with vehicle standard. Values are mean ± SEM