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- New prospects in skin regeneration and repair using nanophased hydroxyapatite embedded in collagen nanofibersPublication . Ribeiro, Nilza; Sousa, Aureliana; Cunha-Reis, Cassilda; Oliveira, Ana Leite; Granja, Pedro L.; Monteiro, Fernando J.; Sousa, SusanaThis study reflects an exploitation of a composite matrix produced by electrospinning of collagen and electrospraying of nanophased hydroxyapatite (nanoHA), for skin regeneration applications. The main goal was to evaluate the effect of nanoHA, as source of localized calcium delivery, on human dermal fibroblasts, keratinocytes, and human mesenchymal stem cells (hMSCs) growth, proliferation, differentiation, and extracellular matrix production. This study revealed that calcium ions provided by nanoHA significantly enhanced cellular growth and proliferation rates and prevented adhesion of pathogenic bacteria strains typically found in human skin flora. Moreover, hMSCs were able to differentiate in both osteogenic and adipogenic lineages. Rat subcutaneous implantation of the membranes also revealed that no adverse reaction occurred. Therefore, the mechanically fit composite membrane presents a great potential to be used either as cell transplantation scaffold for skin wound regeneration or as wound dressing material in plastic surgery, burns treatment or skin diseases.
- Ultrasound sonication prior to electrospinning tailors silk fibroin/PEO membranes for periodontal regenerationPublication . Serôdio, Ricardo; Schickert, Sónia L.; Costa-Pinto, Ana R.; Dias, Juliana R.; Granja, Pedro L.; Yang, Fang; Oliveira, Ana L.In this study, silk fibroin (SF)/poly(ethylene oxide) (PEO) membranes were designed and fabricated by combining ultrasound sonication prior to electrospinning (0 to 20 min) as a strategy to physically control the rheological properties of solutions (10 to 30% w/v PEO) and to improve the spinnability of the system. PEO has proved to be essential as a co-spinning agent to assure good membrane reproducibility and enough flexibility for clinical manipulation. The rheological tests indicated that sonication greatly increased the viscosity of SF/PEO solutions and further enhanced the quality of the produced electrospun fibers with consequent improved mechanical properties in dry and wet conditions. By tuning the viscosity of the solutions using a simple sonication step prior to electrospinning, it was possible to induce water stability in the as-electrospun matrix, as demonstrated by infra-red spectroscopy. This reduced complexity in the process since it was not necessary to concentrate silk prior to electrospinning while avoiding the use of toxic solvents to perform a post-processing stabilization treatment which usually causes dimensional changes to the SF materials. Sonication pre-treatment allowed for minimizing the amount of synthetic polymer used to achieve the desirable mechanical properties (with the modulus ranging between 90 and 170 MPa), while avoiding a further water stabilization treatment. It also had a positive impact in the in vitro cell behavior of human primary periodontal ligament cells (hPDLs), resulting in a marked increase in cell proliferation. The present developed work constitutes a step forward towards simplicity and a better fabrication control of viable electrospun SF-based membranes for periodontal regeneration.