Artikel
Controlled release of rAAV-2 viral vectors from alginate-poloxamer complex systems
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Veröffentlicht: | 5. Oktober 2015 |
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Gliederung
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Objectives: Inclusion of viral vectors in polymeric systems is an attractive approach to enhance their stability and efficacy and decrease potential neutralizing immune responses. We developed different alginate-poloxamer hydrogel structures to entrap and release rAAV vectors for the genetic modification of hMSCs, a key population for regenerative medicine.
Methods: hMSCs were isolated from bone marrow aspirates obtained from the distal femurs of donors undergoing total knee arthroplasty. rAAV-lacZ carries the E. coli β-galactosidase (lacZ) gene. Polymer dispersions were prepared using 0.3% alginate (AlgPH155) or 0.3% alginate/9% thermosensitive poloxamer Pluronic F127® (AlgPH155 + PF127). Dispersions were dropped with rAAV-lacZ in calcium chloride for crosslinking of alginate to produce capsules at room temperature (AlgPH155 + PF127 [C]) or at 50°C (AlgPH155 + PF127 [H]). Capsule stability (weight, size) was monitored upon immersion in culture medium with or without hMSCs. Spectrophotometry analyses were performed to measure rAAV entrapment in the capsules and rAAV release in the culture medium from the capsules. Viability and gene transfer efficiencies upon contact of hMSCs with the capsules was determined using the Cell Proliferation Reagent WST-1 and the Beta-Glo Assay System, respectively. All experiments were performed in quintuplicate for each condition and time point. Statistical significant differences between treatments were evaluated by ANOVA. P values below 0.05 were considered statistically significant.
Results and Conclusion: Interactions between Pluronic F127® and alginate allowed to produce different hydrogel porous structures depending on the crosslinking temperature. All hydrogels were capable of loading and releasing rAAV, showing different release profiles according to their structure. High levels of cell viability were always noted upon contact between hMSCs and the capsules. The rAAV transduction efficiencies in hMSCs placed in contact with the loaded capsules were concordant with the vector release profiles, capsule stability, and porous structure. The presence of Pluronic F127® enhanced the transduction efficiencies on day 1, probably due to a change in membrane permeability. Alginate decreased the levels of transgene expression, possibly due to a lesser diffusion of rAAV, yet this was not seen with crosslinked (AlgPH155 + PF127) capsules that were capable of loading and releasing rAAV in a controlled manner, achieving high levels of transgene expression. These findings show the potential of using such hydrogel structures to promote the safe and effective delivery of rAAV vectors to hMSCs. Such an approach has strong value to deliver chondroregenerative genes in hMSCs as future tools to enhance articular cartilage repair.