SBIR-STTR Award

The principal aim of this proposal is to deliver a sustained release, polymeric agent to prevent collagen accumulation in hypertensive blood vessels. The polymer, a backbone of alternating PEG2000 and lysine with the proline analogue cis-4-hydroxy-L-prol ine (cHyp) attached to the lysine group, has sustained, specific antifibrotic activity. It is proposed to redesign the polymer by using PEG1000 in place of PEG2000 to increase drug "loading" of the polymer. Because of the size of the p olymer (Mr=21,000d), liposomes are required for uptake by endothelial cells and a polysaccharide -coated liposome will be employed to enhance cell uptake. Retention of the polymer/liposome delivery system will be tested using an endothelial cell/smooth muscle cell (SMC) coculture system. Uptake of the delivery system by endothelial cells, stability of the polymer in cells and release of the active agent to SMCs to inhibit collagen synthesis will be studied. Another experiment will evaluate the effects of i.v. infused polymer in polysaccharide-coated liposomes on vascular collagen accumulation and pulmonary hypertension in rats exposed to hypoxia (10% O2). Results will be compared to treatment with nonbioactive trans-Hyp polymer. The strategy to locally deliver a sustained release collagen inhibitor may be applied to various fibrosing disorders.

Thesaurus Terms:
biomaterial development /preparation, drug delivery system, polymer, pulmonary hypertension, slow release drug antifibrinolytic agent, cardiovascular disorder chemotherapy, collagen, drug design /synthesis /production, hydroxyproline, liposome, nonhuman therapy evaluation, protein metabolism, respiratory disorder chemotherapy, vascular endothelium, vascular smooth muscle laboratory rat, mixed tissue /cell cultureNational Heart, Lung and Blood Institute (NHLBI)

In our previous studies, proline analogues such as cis-4-hydroxy-L-proline (cHyp, a potent inhibitor of collagen synthesis) have been attached to a class of water soluble polymers which were found to sustain release, reduce toxicity, and increase antifibrotic potency. The water soluble polymer consists of an alternating copolymer of low molecular wt polyethylene glycol (PEG) and the amino acid lysine (Lys), which provides an attachment site for cHyp, making a poly [PEG-Lys-cHyp] conjugate. cHyp is one of a series of proline analogues which have been shown to be a potent inhibitor of synthesis of collagen, and thus has been considered as a potential antifibrotic agent. Because of the size of the polymer (MW = 21,000 d) liposomes are required for cellular uptake. It was found that uptake by endothelial cells, and subsequently uptake in vivo, was enhanced by using a polysaccharide-coated liposome construct. Using a series of cell culture and in vivo studies, the Phase l results showed that the liposomal encapsulated poly[PEG-Lys-cHyp] was effective in decreasing into the right ventricular pressure and pulmonary artery collagen deposition that resulted from experimentally induced pulmonary hypertension. The goal of these proposed Phase Il studies is to further develop the compound formulation and to begin pre-clinical efficacy, toxicity, and safety studies. As in Phase I, the formulation and any modifications will be tested using cell culture and in vivo assays to determine the potential safety and bioactivity of this compound. PROPOSED COMMERCIAL APPLICATION: Currently, there are no effective treatments for pulmonary hypertension. Supplemental oxygen therapy increases longevity, but does not reverse the disease. General vasodilators such as hydralazine and the prostacyclin analogue epoprostenol have been used, but are only marginally effective. Although there are a number of companies which are developing antifibrotic agents, there is no competition, to the management's knowledge, for a site-directed therapeutic agent to combat pulmonary hypertension.

Thesaurus Terms:
drug delivery system, drug design /synthesis /production, hydroxyproline, polymer, pulmonary hypertension, slow release drug antifibrinolytic agent, cardiovascular disorder chemotherapy, collagen, drug screening /evaluation, liposome, polyethylene glycol, respiratory disorder chemotherapy, vascular endothelium laboratory rat, tissue /cell culture