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Bone-marrow-derived mesenchymal stem cells (BMSCs) are a promising source of cells for tissue engineering due to their multilineage mesenchymal differentiation potential. Their ability to proliferate and differentiate into the osteogenic, chondrogenic, and adipogenic lineage makes them an attractive cell source as compared to the terminally differentiated cells. In tissue engineering, use of cell sheet technology is gaining popularity. It is based on culturing cells until hyperconfluence, and it has resulted in the reduction of the number of cells lost when seeding onto scaffolds. Thus, formation of cell sheets with multipotent cells, such as BMSCs, would be a promising alternative to the conventional method of cell seeding, that is, single-cell suspension. However, the multilineage potential of BMSC cell sheets has yet to be verified. Therefore, the aim of this study was to characterize the formation of a hyperconfluent BMSC cell sheet as well as the effects of the hyperconfluent culture conditions on the multipotentiality of BMSCs. Our results showed that the BMSC cell sheets remained viable. The cell sheets were rich with type I collagen and were shown to have retained their multipotentiality. Hence, the use of BMSC cell sheets for tissue engineering application seems promising.

The depletion of chondroitin sulfates (CSs) within the intervertebral disc (IVD) during degenerative disc disease (DDD) results in a decrease in tissue hydration, a loss of fluid movement, cell apoptosis, a loss of nerve growth inhibition and ultimately, the loss of disc function. To date, little is known with regards to the structure and content of chondroitin sulfates (CSs) during IVD ageing. The behavior of glycosaminoglycans (GAGs), specifically CSs, as well as xylosyltransferase I (XT-I) and glucuronyltransferase I (GT-I), two key enzymes involved in CS synthesis as a primer of glycosaminoglycan (GAG) chain elongation and GAG synthesis in the nucleus pulposus (NP), respectively, were evaluated in a bovine ageing IVD model. Here, we showed significant changes in the composition of GAGs during the disc ageing process (6-month-old, 2-year-old and 8-year-old IVDs representing the immature to mature skeleton). The CS quantity and composition of annulus fibrosus (AF) and NP were determined. The expression of both XT-I and GT-I was detected using immunohistochemistry. A significant decrease in GAGs was observed during the ageing process. CSs are affected at both the structural and quantitative levels with important changes in sulfation observed upon maturity, which correlated with a decrease in the expression of both XT-I and GT-I. A progressive switch of the sulfation profile was noted in both NP and AF tissues from 6 months to 8 years. These changes give an appreciation of the potential impact of CSs on the disc biology and the development of therapeutic approaches for disc regeneration and repair.

Cellular morphology has recently been indicated as a powerful indicator of cellular function. The analysis of cell shape has evolved from rudimentary forms of microscopic visual inspection to more advanced methodologies that utilize high-resolution microscopy coupled with sophisticated computer hardware and software for data analysis. Despite this progress, there is still a lack of standardization in quantification of morphometric parameters. In addition, uncertainty remains as to which methodologies and parameters of cell morphology will yield meaningful data, which methods should be utilized to categorize cell shape, and the extent of reliability of measurements and the interpretation of the resulting analysis. A large range of descriptors has been employed to objectively assess the cellular morphology in two-dimensional and three-dimensional domains. Intuitively, simple and applicable morphometric descriptors are preferable and standardized protocols for cell shape analysis can be achieved with the help of computerized tools. In this review, cellular morphology is discussed as a descriptor of cellular function and the current morphometric parameters that are used quantitatively in two- and three-dimensional environments are described. Furthermore, the current problems associated with these morphometric measurements are addressed. Copyright © 2015 John Wiley & Sons, Ltd.

Background context Intervertebral discs (IVD) are attractive targets for local drug delivery because they are avascular structures with limited transport. Painful IVDs are in a chronic inflammatory state. While anti-inflammatories show poor performance in clinical trials their efficacy treating IVD cells suggests that sustained, local drug delivery directly to painful IVDs may be beneficial. Purpose To determine if genipin crosslinked fibrin (FibGen) with collagen type I hollow spheres (CHS) can serve as a drug delivery carrier for the anti-TNFα drug, infliximab. Infliximab was chosen as a model drug because of the known role of TNFα in increasing downstream production of several pro-inflammatory cytokines and pain mediators. FibGen was used as drug carrier because it is adhesive injectable, slowly degrading hydrogel with potential to seal annulus fibrosus (AF) defects. CHS allow simple and non-damaging drug loading and could act as a drug reservoir to improve sustained delivery. Study Design/Setting Biomaterials and human AF cell culture study to determine drug release kinetics and efficacy. Methods Infliximab was delivered at low and high concentrations using FibGen with and without CHS. Gels were analyzed for structure, drug release kinetics, and efficacy treating human AF cells following release. This work was funded by grants from the NIAMS/NIH (R01 AR057397), AO Foundation, and from the Icahn School of Medicine at Mount Sinai. Results Fibrin showed rapid infliximab drug release but degraded quickly. CHS alone showed a sustained release profile but the small spheres may not remain in a degenerated IVD with fissures. FibGen showed steady and low levels of infliximab release that was increased when loaded with higher drug concentrations. Infliximab was bound in CHS when delivered within FibGen and was only released following enzymatic degradation. The infliximab released over 20 days retained its bioactivity as confirmed by the sustained reduction of IL-1β, IL-6, IL-8, and TNFα concentrations produced by AF cells. Conclusions Direct mixing of infliximab into FibGen was the simplest drug loading protocol capable of sustained release. Results show feasibility of using drug-loaded FibGen for delivery of infliximab and, in the context with the literature, show potential to seal AF defects and partially restore IVD biomechanics. Future investigations are required to determine if drug-loaded FibGen can effectively deliver drugs, seal AF defects, and promote IVD repair or prevent further IVD degeneration in vivo.