Multiple platelet-rich plasma preparations can solubilize freeze-dried chitosan formulations to form injectable implants for orthopedic indications

BACKGROUND: Platelet-rich plasma (PRP) has been used to solubilize freeze-dried chitosan (CS) formulations to form injectable implants for tissue repair. OBJECTIVE: To determine whether the in vitro performance of the formulations depends on the type of PRP preparation used to solubilize CS. METHODS: Formulations containing 1% (w/v) CS with varying degrees of deacetylation (DDA 80.5-84.8%) and number average molar mass (Mn 32-55 kDa), 1% (w/v) trehalose and 42.2 mM calcium chloride were freeze-dried. Seven different PRP preparations were used to solubilize the formulations. Controls were recalcified PRP. RESULTS: CS solubilization was achieved with all PRP preparations. CS-PRP formulations were less runny than their corresponding PRP controls. All CS-PRP formulations had a clotting time below 9 minutes, assessed by thromboelastography, while the leukocyte-rich PRP controls took longer to coagulate (> 32 min), and the leukocyte-reduced PRP controls did not coagulate in this dynamic assay. In glass culture tubes, all PRP controls clotted, expressed serum and retracted (43-82% clot mass lost) significantly more than CS-PRP clots (no mass lost). CS dispersion was homogenous within CS-PRP clots. CONCLUSIONS: In vitro performance of the CS-PRP formulations was comparable for all types of PRPs assessed.