Nanomaterials in Stem Cell Regenerative Medicine: The Scaffold-Based Approach

Background and Aim: Rapid progress in biomaterial engineering has aprofound impact on tissue engineering and regenerative medicine. Theapplication of nanotechnology to regenerative medicine is a wide issue.Nanotechnology can provide new strategies for regenerative medicine,including better tools to improve or repair damaged tissues. The adhesion,growth, and differentiation of stem cells are controlled by nanotopographyof their surrounding microenvironment or the architecture of scaffoldsthat forms a network for human tissues. Nanostructured materials suchas nanocomposites and nanofibers have attracted increasing interestin regenerative medicine, because these nanomaterials can mimicthe physical characteristics of the natural extracellular matrix (ECM)at the nanoscale level. Nanofibers, have been used as scaffolds formusculoskeletal tissue engineering (including bone, cartilage, ligament,and skeletal muscle), skin tissue engineering, vascular tissue engineering,and neural tissue engineering. In this study we will present thepreparation and evaluation of electrospun nanofibrous scaffolds for stemcell differentiation and tissue regeneration. We have prepared variousbiodegradable blends of natural and synthetic polymers for scaffoldfabrication with the ability to increase cell survival, proliferation, andmigration and provide supporting mechanical properties by mimickingthe ECM.Methods: Biodegradable blends of natural polymers such as collagen,gelatin and chitosan with biodegradable polyesters such as poly(L-lactide)(PLLA), poly(glycolide) (PGA), poly (ɛ- caprolactone) (PCL), poly(lactideco-glycolide) (PLGA) and poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ -caprolactone) (PCL-PEG-PCL, PCEC) have been prepared asnanofibrous scaffolds and incorporated with appropriate nanoparticlessuch as hydroxyapatite (HA), silica nanoparticles (n-SiO2), magneticnanoparticles (MNPs), and growth factor-loaded polymericnanoparticles for the creation of 3D cell-supportive scaffolds. Inanother approach, different thermosensitive hydrogels, based on poly(N-isopropylacrylamide; PNIPAAm) copolymers, have been developedand used as injectable implants. The biocompatibility, morphology,proliferation and differentiation abilities of human mesenchymal stemcells on these nanostructured scaffolds have been investigated. Theapplications of these nanostructured scaffolds have been evaluated forbone, cartilage and skin regeneration.Results: Blends of natural polymers such as gelatin, chitosan and collagenwith biodegradable polymers exhibit improved mechanical properties and provide an effective, non-toxic approach for the fabrication ofbiomimetic scaffolds for tissue engineering. The incorporation ofmagnetic nanoparticles and/or HA can promote osteointegrationand osteoinduction. The polyester-collagen hybrid nanofibrousscaffold provides a stimulus microenvironment for the chondrogenicdifferentiation of the MSCs. The PCL-PEG-PCL/ CS/ n-SiO2 and n-HA withan average diameter in the range of 190–260 nm showed excellent celladhesion and proliferation properties. Alizarin red S staining and qRT-PCRanalysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CSnanofibers incorporated with n-HA and n-SiO2. Thermosensitive PCEC/Gel and (PNIPAAm-PCEC-PNIPAAm)/Gel hydrogel scaffolds possessesuseful hydrophilic properties for the growth and cell embedding andsecretion of extracellular matrix. It can serve as an ideal strategy topromote the formation of cartilage tissue.Conclusion: Development of biomaterials is important for scaffoldfabrication. Electrospun blend nanofibrous scaffolds have a high surfacearea to volume ratio, controllable diameter and porosity, excellentbiological activity and can provide an appropriate architecture for bone,cartilage and skin tissue engineering.

کلیدواژه ها:

Nanomaterials ، Electrospun nanofibers ، Scaffolds ، Tissueengineering