A collagen prolyl 4-hydroxylase inhibitor reduces adhesions after tendon injury.

Collagen synthesis inhibition potentially can reduce adhesion formation after tendon injury but also may affect cutaneous wound healing. We hypothesized that a novel orally administered collagen synthesis inhibitor (CPHI-I) would substantially reduce flexor tendon adhesions after injury, without any clinically important effect on cutaneous wound healing. The experiments were performed in a rat model with an in-continuity crush injury model in the rat hindfoot flexor tendon to provoke adhesion formation. Assays of dermal collagen production and the rate of healing of an excised wound were performed to assess cutaneous wound healing. Animals in the treatment groups received CPHI-I for 1, 2, or 6 weeks and were assessed at either 2 or 6 weeks. The work of flexion in the injured digit was reduced in the CPHI-I-treated animals compared with control animals, (0.188 J versus 0.0307 J at 2 weeks, and 0.0231 J versus 0.0331 J at 6 weeks) The cutaneous wound healing rate was similar in all animals, but dermal collagen synthesis was reduced in the treated animals. The CPHI-I seems to reduce tendon adhesion, and although collagen synthesis was reduced in cutaneous wounds, CPHI-I did not retard wound healing.

In vitro evaluation of microparticles and polymer gels for use as nasal platforms for protein delivery.

PURPOSE: Nasal delivery of protein therapeutics can be compromised by the brief residence time at this mucosal surface. Some bioadhesive polymers have been suggested to extend residence time and improve protein uptake across the nasal mucosa. We examined several potential polymer platforms for their in vitro protein release, relative bioadhesive properties and induction of cytokine release from respiratory epithelium. METHODS: Starch, alginate, chitosan or Carbopol microparticles, containing the test protein bovine serum albumin (BSA), were prepared by spray-drying and characterized by laser diffraction and scanning electron microscopy. An open-membrane system was used to determine protein release profiles and confluent, polarized Calu-3 cell sheets were used to evaluate relative bioadhesion, enhancement of protein transport and induction of cytokine release in vitro. RESULTS: All spray-dried microparticles averaged 2-4 microm in diameter. Loaded BSA was not covalently aggregated or degraded. Starch and alginate microparticles released protein more rapidly but were less adhesive to polarized Calu-3 cells than chitosan and Carbopol microparticles. Protein transport across polarized Calu-3 cells was enhanced from Carbopol gels and chitosan microparticles. A mixture of chitosan microparticles with lysophosphatidylcholine increased protein transport further. Microparticles prepared from either chitosan or starch microparticles, applied apically, induced the basolateral release of IL-6 and IL-8 from polarized Calu-3 cells. Release of other cytokines, such as IL-1beta, TNF-alpha, GM-CSF and TGF-beta, were not affected by an apical exposure to polymer formulations. CONCLUSIONS: We have described two systems for the in vitro assessment of potential nasal platforms for protein delivery. Based upon these assessments, Carbopol gels and chitosan microparticles provided the most desirable characteristics for protein therapeutic and protein antigen delivery, respectively, of the formulations examined.

Influence of the microencapsulation method and peptide loading on poly(lactic acid) and poly(lactic-co-glycolic acid) degradation during in vitro testing.

Three methods were used, namely spray drying, w/o/w solvent evaporation and the aerosol solvent extraction system (ASES), for the preparation of microparticles having the same size range, to study the influence of the preparation method on polymer degradation in vitro (PBS, 37 degrees C, one month). The following five polymers of the biodegradable poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) group were selected: L-PLA, MW 81 200; DL-PLGA 75:25, MW 64-300; DL-PLGA 50:50 MW 52 600; DL-PLGA 50:50 MW 14 500, AND DL-PLGA 50:50, MW 3400, to prepare drug-free and drug-loaded microparticles. Tetracosactide was selected as model peptide. When microparticles were prepared by solvent evaporation, the mean diameter and, more markedly, the drug encapsulation efficiency tended to decrease when decreasing the molecular weight and increasing the proportion of glycolic acid in the polymer. In contrast, no direct influence of the polymer nature on these parameters was observed in spray dried microparticles. Polymer degradation was heterogenous in L-PLA and DL-PLGA 75:25 microparticles and was not influenced by the presence of the drug at a nominal loading of 1% (w/w), when prepared by the three methods (note that with ASES, only L-PLA could be used for microencapsulation). In batches made of DL-PLGA 50:50 MW 52 600, the degradation rate decreased slightly when increasing the drug loading. Only in the case of DL-PLGA 50:50 MW 14 500, the polymer degradation rate for spray dried microparticles was higher compared to that for microparticles prepared by the w/o/w solvent evaporation method. Generally, the degradation rates of the different microparticles followed the expected order: L-PLA