A biodegradable polyurethane‐ascorbic acid scaffold for bone tissue engineering

Abstract

A novel, nontoxic, biodegradable, sponge-like polyurethane scaffold was synthesized from lysine-di-isocyanate (LDI) and glycerol. Ascorbic acid (AA) was copolymerized with LDI-glycerol. Our hypothesis was that the AA-containing polymer foam would enhance the biological activity of the osteoblastic precursor cell (OPCs). The LDI-glycerol-AA matrix degraded in aqueous solution to the nontoxic products of lysine, glycerol, and AA. The degradation products did not significantly affect the solution pH. The physical properties of the polymer network supported the cell growth in vitro. Mouse OPCs attached to the polymer matrix and remained viable. OPCs produced multilayered confluent cultures, a characteristic typical of bone cells. Furthermore, AA release stimulated cell proliferation, type I collagen, and alkaline phosphatase synthesis. Cells grown on the LDI-glycerol-AA matrix also showed an enhancement of mRNA expression for pro-alpha1 (I) collagen and transforming growth factor-alpha1 after 1 week. Data were tested for significance with an analysis of variance model and multiple comparison test (Fisher's Protected Least Significant Difference) at p < or = 0.05. The observations suggest that AA-containing polyurethane may be useful in bone tissue engineering applications.

Injectable Biodegradable Polyurethane Scaffolds with Release of Platelet-derived Growth Factor for Tissue Repair and Regeneration

“…However, in this study, the bFGF was released from a pre-formed polymer scaffold, not from a reactive polymer. PUR scaffolds prepared by reactive liquid molding of LDI, glycerol, water, and ascorbic acid (AA) have been shown to support controlled release of AA over 60 days (51). By dissolving the AA in the glycerol prior to adding the LDI, the AA was covalently bound to the polymer through reaction of the primary hydroxyl group in the AA with LDI to form urethane linkages.…”

Thermal and mechanical properties of polyurethanes modified with L-ascorbic acid

“…Ascorbic acid has large impact on tissues regeneration due to improving collagen synthesis [20], which is a component of the primary extracellular matrix (ECM) [21], which supports cells attachment, growth, and proliferation [22]. Some literature data show that researchers took an attempt to incorporate AA into the polyurethane structure to improve the material biocompatibility and biodegradability [23,24].…”

“…In case of using AA as a polyurethane chain modifier, it would be also subjected to thermal treatment such as polyurethane synthesis and curing (both carried out at 80°C). Thermal stability is of particular interest, because of the thermal decomposition kinetics studies, which may lead to improvement in ascorbic acid stability, which is important especially considering the context of pharmaceuticals, food products [18], and recently medical devices, modified with ascorbic acid [23,24]. In the literature are available degradation studies of ascorbic acid, carried out under different conditions, such as in different solvents [30], in steam [31], in food [20], under oxygenated conditions [32] and under inert conditions [33].…”

Ascorbic Acid in Polyurethane Systems for Tissue Engineering

“…The amount of hard segments influences the degree of phase separation, which in turn affects physical and mechanical properties [30], degradation rate and biocompatibility [32][33]. By varying the molecular weight of polyol and the composition of the different segments, properties of PUR can be tuned up for use in many areas of TE [34][35][36][37][38]. In this respect, the range of mechanical and morphological properties that can be obtained with PUR is significantly larger than with commonly used medical grade biodegradable polymers for example: PLA, PGA, poly(DL-lactide) (PDLLA) [39][40][41][42].…”

“…During the studies they showed that obtained LDI-glycerol-L-AA matrix degrade in aqueous solution to the nontoxic products of lysine, glycerol, and L-AA. The degradation products did not significantly affect the pH solution and physical properties [37]. Mouse osteoblastic precursor cells (OPCs), which they used to attach to the polymer matrix, remained viable.…”