title: Sustained release formulations of rhVEGF₁₆₅ produce a durable response in a murine model of peripheral angiogenesis.
abstract: Local delivery of therapeutic angiogenic agents that stimulate blood vessel formation represents a promising strategy for the treatment of peripheral vascular disease (PVD). At present, requirements for temporal and spatial parameters for localized delivery are unclear, with a variety of sustained delivery approaches being examined. Two polymer-based sustained formulations containing the 165 amino acid isoform of human recombinant vascular endothelial growth factor-A (rhVEGF(165)) were evaluated for their potential application in the treatment of PVD following intramuscular injection. Microspheres prepared from a 50:50 ratio of polylactic-co-glycolic acid (PLGA) and a gel of PLGA polymer solubilized in N-methyl pyrrolidone (PLGA:NMP) were each loaded with rhVEGF(165) and tested in vitro and in vivo. PLGA microspheres averaged ∼30 μm in diameter and contained 8.9% (w/w) rhVEGF(165), while the PLGA:NMP gel was formulated with varying amounts of spray freeze-dried rhVEGF(165) to result in final gel formulations having concentrations of 0.36, 0.72, or 3.6 mg/mL rhVEGF(165). In vitro release of rhVEGF(165) from PLGA microspheres showed ∼10% cumulative release by day 6, whereas the cumulative release of rhVEGF(165) from the PLGA:NMP gel matrices (0.65% w/w loading) was less than 0.25% at this same time point. While the in vitro release characteristics of these two sustained release formulations were broadly different, the plasma rhVEGF(165) concentration-time profiles following hind-limb intramuscular (IM) injection of these formulations in non-compromised rats revealed similar in vivo pharmacokinetics. Three-dimensional resin casts of vascular architecture were prepared at days 3, 7, 14, 21, 28, 60, and 75 following a single IM dosing of these sustained release microsphere and gel matrix formulations in the gastrocnemius muscle of immune-compromised mice. Scanning electron microscopic visualization of these vascular casts demonstrated spatial arrangement of capillary sprouts and vessel enlargement consistent with profound vascular changes occurring within 3 days of dosing that persisted for 2 months, approximately 1 month beyond the anticipated completion of rhVEGF(165) release from these sustained delivery formulations. Vascular re-modeling events were correlated with histological and immunohistochemical parameters attributed to known biological actions of rhVEGF(165) signaling. Together, these pharmacokinetic and pharmacodynamic results support the use of sustained release PLGA-based formulations for the local delivery of rhVEGF(165) to achieve a durable vascular re-modeling response.
authors.affiliation: Genentech Inc., S. San Francisco, CA 94080, USA.
authors.forename: Ann L
authors.initials: AL
authors.lastname: Daugherty
authors.forename: Linda K
authors.initials: LK
authors.lastname: Rangell
authors.forename: Renee
authors.initials: R
authors.lastname: Eckert
authors.forename: Jose
authors.initials: J
authors.lastname: Zavala-Solorio
authors.forename: Frank
authors.initials: F
authors.lastname: Peale
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Mrsny
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000517:prevention & control*; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A