Proliferation and differentiation of human mesenchymal stem cell encapsulated in polyelectrolyte complexation fibrous scaffold.

A biofunctional scaffold was constructed with human mesenchymal stem cells (hMSCs) encapsulated in polyelectrolyte complexation (PEC) fibers. Human MSCs were either encapsulated in PEC fibers and constructed into a fibrous scaffold or seeded on PEC fibrous scaffolds. The proliferation, chondrogenic and osteogenic differentiation of the encapsulated and seeded hMSCs were compared for a culture period of 5.5 weeks. Gene expression and extracellular matrix production showed evidences of chondrogenesis and osteogenesis in the cell-encapsulated scaffolds and cell-seeded scaffolds when the samples were cultured in the chondrogenic and osteogenic differentiation media, respectively. However, better cell proliferation and differentiation were observed on the hMSC-encapsulated scaffolds compared to the hMSC-seeded scaffolds. The study demonstrated that the cell-encapsulated PEC fibers could support proliferation and chondrogenic and osteogenic differentiation of the encapsulated-hMSCs. Together with our previous works, which demonstrated the feasibility of PEC fiber in controlled release of drug, protein and gene delivery, the reported PEC fibrous scaffold system will have the potential in composing a multi-component system for various tissue-engineering applications.

Electrosprayed core-shell microspheres for protein delivery.

This communication describes a single-step electrospraying technique that generates core-shell microspheres (CSMs) with encapsulated protein as the core and an amphiphilic biodegradable polymer as the shell. The protein release profiles of the electrosprayed CSMs showed steady release kinetics over 3 weeks without a significant initial burst.

Sustained viral gene delivery through core-shell fibers.

Although viral gene transfer is efficient in achieving transgene expression for tissue engineering, drawbacks of virus dissemination, toxicity and transient gene expression due to immune response have hindered its widespread application. Many tissue engineering studies thus opt to genetically engineer cells in vitro prior to their introduction in vivo. However, it would be attractive to obviate the need for in vitro manipulation by transducing the infiltrating progenitor cells in situ. This study introduces the fabrication of a virus-encapsulated electrospun fibrous scaffold to achieve sustained and localized transduction. Adenovirus encoding the gene for green fluorescent protein was efficiently encapsulated into the core of poly(epsilon-caprolactone) fibers through co-axial electrospinning and was subsequently released via a porogen-mediated process. HEK 293 cells seeded on the scaffolds expressed high level of transgene expression over a month, while cells inoculated by scaffold supernatant showed only transient expression for a week. RAW 264.7 cells cultured on the virus-encapsulated fibers produced a lower level of IL-1 beta, TNF-alpha and IFN-alpha, suggesting that the activation of macrophage cells by the viral vector was reduced when encapsulated in the core-shell PCL fibers. In demonstrating sustained and localized cell transduction, this study presents an attractive alternative mode of applying viral gene transfer for regenerative medicine.

Nonviral gene delivery from nonwoven fibrous scaffolds fabricated by interfacial complexation of polyelectrolytes.

We investigated a novel nonwoven fibrous scaffold as a vehicle for delivery of DNA. Fibers were formed by polyelectrolyte complexation of water-soluble chitin and alginate, and PEI-DNA nanoparticles were encapsulated during the fiber drawing process. Nanoparticles released from the fibers over time retained their bioactivity and successfully transfected cells seeded on the scaffold in a sustained manner. Transgene expression in HEK293 cells and human dermal fibroblasts seeded on the transfecting scaffolds was significant even after 2 weeks of culture compared to 3-day expression in two-dimensional controls. Fibroblasts seeded on scaffolds containing DNA encoding basic fibroblast growth factor (bFGF) demonstrated prolonged secretion of bFGF at levels significantly higher than baseline. This work establishes the potential of this fibrous scaffold as a matrix capable of delivering genes to direct and support cellular development in tissue engineering.