Bone regeneration after injury or after surgical bone removal due to disease is a serious medical challenge. A variety of materials are being tested to replace a missing bone or tooth. Regeneration requires cells capable of proliferation and differentiation in bone tissue. Although there are many possible human cell types available for use as a model for each phase of this process, no cell type is ideal for each phase. Osteosarcoma cells are preferred for initial adhesion assays due to their easy cultivation and fast proliferation, but they are not suitable for subsequent differentiation testing due to their cancer origin and genetic differences from normal bone tissue. Mesenchymal stem cells are more suitable for biocompatibility testing, because they mimic natural conditions in healthy bone, but they proliferate more slowly, soon undergo senescence, and some subpopulations may exhibit weak osteodifferentiation. Primary human osteoblasts provide relevant results in evaluating the effect of biomaterials on cellular activity; however, their resources are limited for the same reasons, like for mesenchymal stem cells. This review article provides an overview of cell models for biocompatibility testing of materials used in bone tissue research.

• Keywords
• Bone engineering, Human osteoblasts, Mesenchymal stem cells, Osteodifferentiation, Osteosarcoma cell lines,
• MeSH
• Biocompatible Materials pharmacology   MeSH
• Cell Differentiation MeSH
• Bone and Bones * MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Osteoblasts MeSH
• Osteogenesis MeSH
• Cell Proliferation MeSH
• Tissue Engineering * methods   MeSH
• Tissue Scaffolds MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Biocompatible Materials MeSH

The objective of this study was to evaluate and compare titanium surfaces: machined (MA); sintered ceramic-blasted (HAS); sintered ceramic-blasted and acid-etched (HAS DE) and to determine the effects of surface topography, roughness and chemical composition on human osteoblast cell reaction. Titanium surface samples were analyzed with respect to surface chemical composition, topography, and roughness. The effects of material surface characteristics on osteoblasts was examined by analyzing osteoblast morphology, viability and differentiation. Osteoblasts cultured on these materials had attached, spread and proliferated on every sample. The viability of osteoblasts cultured on HAS and HAS DE samples increased more intensively in time comparing to MA sample. The viability of osteoblast cultured on HAS samples increased more intensively in the early phases of culture while for cells cultured on HAS DE the cells viability increased later in time. Alkaline phosphate activity was the highest for the cells cultured on HAS sample and statistically higher than for the MA sample. The least activity occurred on the smooth MA sample along with the rougher HAS DE samples. All the examined samples were found to be biocompatible, as indicated by cell attachment, proliferation, and differentiation. Titanium surfaces modification improved the dynamics of osteoblast viability increase. Osteoblast differentiation was found to be affected by the etching procedure and presence of Ca and P on the surface.

• MeSH
• Alkaline Phosphatase metabolism   MeSH
• Cell Differentiation MeSH
• Cell Line MeSH
• Phosphorus pharmacology   MeSH
• Ceramics MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Osteoblasts physiology   ultrastructure   MeSH
• Osteogenesis drug effects   MeSH
• Surface Properties MeSH
• Cell Proliferation MeSH
• Titanium chemistry   MeSH
• Calcium pharmacology   MeSH
• Cell Survival MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Alkaline Phosphatase MeSH
• Phosphorus MeSH
• Titanium MeSH
• Calcium MeSH

The cytoskeleton plays a key role in cellular proliferation, cell-shape maintenance and internal cellular organization. Cells are highly sensitive to changes in microgravity, which can induce alterations in the distribution of the cytoskeletal and cell proliferation. This study aimed to assess the effects of simulated microgravity (SMG) on the proliferation and expression of major cell cycle-related regulators and cytoskeletal proteins in human umbilical cord mesenchymal stem cells (hucMSCs). A WST-1 assay showed that the proliferation of SMG-exposed hucMSCs was lower than a control group. Furthermore, flow cytometry analysis demonstrated that the percentage of SMG-exposed hucMSCs in the G0/G1 phase was higher than the control group. A western blot analysis revealed there was a downregulation of cyclin A1 and A2 expression in SMG-exposed hucMSCs as well. The expression of cyclin-dependent kinase 4 (cdk4) and 6 (cdk6) were also observed to be reduced in the SMG-exposed hucMSCs. The total nuclear intensity of SMG-exposed hucMSCs was also lower than the control group. However, there were no differences in the nuclear area or nuclear-shape value of hucMSCs from the SMG and control groups. A western blot and quantitative RT-PCR analysis showed that SMG-exposed hucMSCs experienced a downregulation of bata-actin and alpha-tubulin compared to the control group. SMG generated the reorganization of microtubules and microfilaments in hucMSCs. Our study supports the idea that the downregulation of major cell cycle-related proteins and cytoskeletal proteins results in the remodeling of the cytoskeleton and the proliferation of hucMSCs.

• MeSH
• Cell Differentiation physiology   MeSH
• Cell Cycle physiology   MeSH
• Cytoskeleton metabolism   MeSH
• Cells, Cultured MeSH
• Humans MeSH
• Mesenchymal Stem Cells cytology   metabolism   MeSH
• Actin Cytoskeleton metabolism   MeSH
• Microtubules metabolism   MeSH
• Cell Proliferation physiology   MeSH
• Umbilical Cord cytology   metabolism   MeSH
• Weightlessness Simulation * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

Sensorineural hearing loss and vertigo, resulting from lesions in the sensory epithelium of the inner ear, have a high incidence worldwide. The sensory epithelium of the inner ear may exhibit extreme degeneration and is transformed to flat epithelium (FE) in humans and mice with profound sensorineural hearing loss and/or vertigo. Various factors, including ototoxic drugs, noise exposure, aging, and genetic defects, can induce FE. Both hair cells and supporting cells are severely damaged in FE, and the normal cytoarchitecture of the sensory epithelium is replaced by a monolayer of very thin, flat cells of irregular contour. The pathophysiologic mechanism of FE is unclear but involves robust cell division. The cellular origin of flat cells in FE is heterogeneous; they may be transformed from supporting cells that have lost some features of supporting cells (dedifferentiation) or may have migrated from the flanking region. The epithelial-mesenchymal transition may play an important role in this process. The treatment of FE is challenging given the severe degeneration and loss of both hair cells and supporting cells. Cochlear implant or vestibular prosthesis implantation, gene therapy, and stem cell therapy show promise for the treatment of FE, although many challenges remain to be overcome.

• MeSH
• Epithelium injuries   pathology   MeSH
• Epithelial-Mesenchymal Transition MeSH
• Noise adverse effects   MeSH
• Humans MeSH
• Hearing Loss, Sensorineural metabolism   pathology   MeSH
• Ear, Inner injuries   metabolism   pathology   MeSH
• Hair Cells, Auditory, Inner metabolism   pathology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH