Maryam Rezai Rad

Polymeric scaffolds in tissue engineering: a literature review

The tissue engineering scaffold acts as an extracellular matrix that interacts to the cells prior to forming new tissues. The chemical and structural characteristics of scaffolds are major concerns in fabricating of ideal three-dimensional structure for tissue engineering applications. The polymer scaffolds used for tissue engineering should possess proper architecture and mechanical properties in addition to supporting cell adhesion, proliferation, and differentiation. Much research has been done on the topic of polymeric scaffold properties such as surface topographic features (roughness and hydrophilicity) and scaffold microstructures (pore size, porosity, pore interconnectivity, and pore and fiber architectures) that influence the cell-scaffold interactions. In this review, efforts were given to evaluate the effect of both chemical and structural characteristics of scaffolds on cell behaviors such as adhesion, proliferation, migration, and differentiation. This review would provide the fundamental information which would be beneficial for scaffold design in future.

Polymeric vs hydroxyapatite-based scaffolds on dental pulp stem cell proliferation and differentiation.

AIM To evaluate adhesion, proliferation and differentiation of human dental pulp stem cells (hDPSCs) on four commercially available scaffold biomaterials. METHODS hDPSCs were isolated from human dental pulp tissues of extracted wisdom teeth and established in stem cell growth medium. hDPSCs at passage 3-5 were seeded on four commercially available scaffold biomaterials, SureOss (Allograft), Cerabone (Xenograft), PLLA (Synthetic), and OSTEON II Collagen (Composite), for 7 and 14 d in osteogenic medium. Cell adhesion and morphology to the scaffolds were evaluated by scanning electron microscopy (SEM). Cell proliferation and differentiation into osteogenic lineage were evaluated using DNA counting and alkaline phosphatase (ALP) activity assay, respectively. RESULTS All scaffold biomaterials except SureOss (Allograft) supported hDPSC adhesion, proliferation and differentiation. hDPSCs seeded on PLLA (Synthetic) scaffold showed the highest cell proliferation and attachment as indicated with both SEM and DNA counting assay. Evaluating the osteogenic differentiation capability of hDPSCs on different scaffold biomaterials with ALP activity assay showed high level of ALP activity on cells cultured on PLLA (Synthetic) and OSTEON II Collagen (Composite) scaffolds. SEM micrographs also showed that in the presence of Cerabone (Xenograft) and OSTEON II Collagen (Composite) scaffolds, the hDPSCs demonstrated the fibroblastic phenotype with several cytoplasmic extension, while the cells on PLLA scaffold showed the osteoblastic-like morphology, round-like shape. CONCLUSION PLLA scaffold supports adhesion, proliferation and osteogenic differentiation of hDPSCs. Hence, it may be useful in combination with hDPSCs for cell-based reconstructive therapy.

Application of selected scaffolds for bone tissue engineering: a systematic review

PurposeThe current systematic review investigated the results of application of some of the most commonly used scaffolds in conjugation with stem cells and growth factors in animal and clinical studies.MethodsA comprehensive electronic search was conducted according to the PRISMA guidelines in NCBI PMC and PubMed from January 1970 to December 2015 limited to English language publications with available full texts. In vivo studies in relation to “bone healing,” “bone regeneration,” and at least one of the following items were investigated: allograft, β-tricalcium phosphate, deproteinized bovine bone mineral, hydroxyapetite/tricalcium phosphate, nanohydroxyapatite, and composite scaffolds.ResultsA total of 1252 articles were reviewed, and 46 articles completely fulfilled the inclusion criteria of this study. The highest bone regeneration has been achieved when combination of all three elements, given scaffolds, mesenchymal stem cells, and growth factors, were used. Among studies being reported in this review, bone marrow mesenchymal stem cells are the most studied mesenchymal stem cells, β-tricalcium phosphate is the most frequently used scaffold, and platelet-rich plasma is the most commonly used growth factor.ConclusionThe current review aimed to inform reconstructive surgeons of how combinations of various mesenchymal stem cells, scaffolds, and growth factors enhance bone regeneration. The highest bone regeneration has been achieved when combination of all three elements, given scaffolds, mesenchymal stem cells, and growth factors, were used.

Fabrication of a three-dimensional β-tricalcium-phosphate/gelatin containing chitosan-based nanoparticles for sustained release of bone morphogenetic protein-2: Implication for bone tissue engineering.

Fabrication of an ideal scaffold having proper composition, physical structure and able to have sustained release of growth factors still is challenging for bone tissue engineering. Current study aimed to design an appropriate three-dimensional (3-D) scaffold with suitable physical characteristics, including proper compressive strength, degradation rate, porosity, and able to sustained release of bone morphogenetic protein-2 (BMP2), for bone tissue engineering. A highly porous 3-D β-tricalcium phosphate (β-TCP) scaffolds, inside of which two perpendicular canals were created, was fabricated using foam-casting technique. Then, scaffolds were coated with gelatin layer. Next, BMP2-loaded chitosan (CS) nanoparticles were dispersed into collagen hydrogel and filled into the scaffold canals. Physical characteristics of fabricated constructs were evaluated. Moreover, the capability of given construct for bone regeneration has been evaluated in vitro in interaction with human buccal fat pad-derived stem cells (hBFPSCs). The results showed that gelatin-coated TCP scaffold with rhBMP2 delivery system not only could act as a mechanically and biologically compatible framework, but also act as an osteoinductive graft by sustained delivering of rhBMP2 in a therapeutic window for differentiation of hBFPSCs towards the osteoblast lineage. The proposed scaffold model can be suggested for delivering of cells and other growth factors such as vascular endothelial growth factor (VEGF), alone or in combination, for future investigations.

Induced pluripotent stem cells as a new getaway for bone tissue engineering: A systematic review.

Mesenchymal stem cells (MSCs) are frequently used for bone regeneration, however, they are limited in quantity. Moreover, their proliferation and differentiation capabilities reduce during cell culture expansion. Potential application of induced pluripotent stem cells (iPSCs) has been reported as a promising alternative source for bone regeneration. This study aimed to systematically review the available literature on osteogenic potential of iPSCs and to discuss methods applied to enhance their osteogenic potential.

Buccal Fat Pad as a Potential Source of Stem Cells for Bone Regeneration: A Literature Review

Adipose tissues hold great promise in bone tissue engineering since they are available in large quantities as a waste material. The buccal fat pad (BFP) is a specialized adipose tissue that is easy to harvest and contains a rich blood supply, and its harvesting causes low complications for patients. This review focuses on the characteristics and osteogenic capability of stem cells derived from BFP as a valuable cell source for bone tissue engineering. An electronic search was performed on all in vitro and in vivo studies that used stem cells from BFP for the purpose of bone tissue engineering from 2010 until 2016. This review was organized according to the PRISMA statement. Adipose-derived stem cells derived from BFP (BFPSCs) were compared with adipose tissues from other parts of the body (AdSCs). Moreover, the osteogenic capability of dedifferentiated fat cells (DFAT) derived from BFP (BFP-DFAT) has been reported in comparison with BFPSCs. BFP is an easily accessible source of stem cells that can be obtained via the oral cavity without injury to the external body surface. Comparing BFPSCs with AdSCs indicated similar cell yield, morphology, and multilineage differentiation. However, BFPSCs proliferate faster and are more prone to producing colonies than AdSCs.

Dental Stem Cells in Oral, Maxillofacial and Craniofacial Regeneration

Regeneration in oral and craniofacial regions includes several specified tissues such as pulp, bone, cartilage, muscle, fat, blood vessels and neurons. Neural crest-derived dental stem cells (DSCs) as a medical waste hold a promise for regeneration in craniofacial region. Five different DSCs have been isolated and characterized: Dental pulp stem cells (DPSCs), stem cells from apical papillae (SCAPs), stem cells obtained from human exfoliated deciduous teeth (SHEDs), dental follicle stem cells (DFSCs) and periodontal ligament stem cells (PDLSCs). These dental tissue- derived stem cells have demonstrated the capability to differentiate towards various cell lineages including adipogenic, chondrogenic, osteogenic, and neurogenic in vitro. Moreover, various studies have shown their potential for regeneration of dentin/pulp, bone, neural, vascular, muscle, cartilage and adipose tissues. Application of DSCs for oral and craniofacial tissues is still in its infancy. However, this chapter will provide insight towards the progress being made regarding utilization of DSCs in oral, maxillofacial and craniofacial regeneration.

Impact of Tissue Harvesting Sites on the Cellular Behaviors of Adipose-Derived Stem Cells: Implication for Bone Tissue Engineering

The advantages of adipose-derived stem cells (AdSCs) over bone marrow stem cells (BMSCs), such as being available as a medical waste and less discomfort during harvest, have made them a good alternative instead of BMSCs in tissue engineering. AdSCs from buccal fat pad (BFP), as an easily harvestable and accessible source, have gained interest to be used for bone regeneration in the maxillofacial region. Due to scarcity of data regarding comparative analysis of isolated AdSCs from different parts of the body, we aimed to quantitatively compare the proliferation and osteogenic capabilities of AdSCs from different harvesting sites. In this study, AdSCs were isolated from BFP (BFPdSCs), abdomen (abdomen-derived mesenchymal stem cells (AbdSCs)), and hip (hip-derived mesenchymal stem cells (HdSCs)) from one individual and were compared for surface marker expression, morphology, growth rate, and osteogenic differentiation capability. Among them, BFPdSCs demonstrated the highest proliferation rate with the shortest doubling time and also expressed vascular endothelial markers including CD34 and CD146. Moreover, the expression of osteogenic markers were significantly higher in BFPdSCs. The results of this study suggested that BFPdSCs as an encouraging source of mesenchymal stem cells are to be used for bone tissue engineering.

In vitro effect of graphene structures as an osteoinductive factor in bone tissue engineering: A systematic review: IN VITRO OSTEOINDUCTIVE EFFECT OF GRAPHENE STRUCTURES

Graphene and its derivatives have been well-known as influential factors in differentiating stem/progenitor cells toward the osteoblastic lineage. However, there have been many controversies in the literature regarding the parameters effect on bone regeneration, including graphene concentration, size, type, dimension, hydrophilicity, functionalization, and composition. This study attempts to produce a comprehensive review regarding the given parameters and their effects on stimulating cell behaviors such as proliferation, viability, attachment and osteogenic differentiation. In this study, a systematic search of MEDLINE database was conducted for in vitro studies on the use of graphene and its derivatives for bone tissue engineering from January 2000 to February 2018, organized according to the PRISMA statement. According to reviewed articles, different graphene derivative, including graphene, graphene oxide (GO) and reduced graphene oxide (RGO) with mass ratio ≤1.5 wt % for all and concentration up to 50 μg/mL for graphene and GO, and 60 μg/mL for RGO, are considered to be safe for most cell types. However, these concentrations highly depend on the types of cells. It was discovered that graphene with lateral size less than 5 µm, along with GO and RGO with lateral dimension less than 1 µm decrease cell viability. In addition, the three-dimensional structure of graphene can promote cell-cell interaction, migration and proliferation. When graphene and its derivatives are incorporated with metals, polymers, and minerals, they frequently show promoted mechanical properties and bioactivity. Last, graphene and its derivatives have been found to increase the surface roughness and porosity, which can highly enhance cell adhesion and differentiation.

Topical erythropoietin as a novel preventive and therapeutic agent in bisphosphonate-related osteonecrosis of the jaw

Introduction: One of the most common side effects of bisphosphonate intake is osteonecrosis of the jaw (ONJ) which may develop following dentoalveolar interventions. Despite the vast available protocols, there is no clear guideline in the management of this condition. In osteonecrosis, the number and proliferation of bone-forming cells as well as vascularity are disturbed. Erythropoietin (EPO) is a hematopoietic hormone with angiogenic, osteogenic, and antiapoptotic properties. The Hypothesis: It is suggested to utilize poly lactic-co-glycolic acid hydrogel containing 1500-3000 IU/kg EPO following dentoalveolar surgery in samples receiving bisphosphonates as a preventive or therapeutic agent. Evaluation of the Hypothesis: Considering the pathophysiology of ONJ and therapeutic properties of EPO, it is assumed that EPO may be effective in treatment of ONJ. Furthermore, as a preventive measure, utilizing EPO following dentoalveolar surgery may be beneficial in the patients at risk of ONJ.