The underlying mechanism appears to be dependent on the FGFR and VEGFR signaling cascades and might be mediated by an additional cross-talk with other pathways. STEM CELLS 2007;25:903-910 Disclosure of potential conflicts of interest is found at the end of this article.

Progenitor cells are involved in the regeneration of the musculoskeletal system, which is known to be influenced by mechanical boundary conditions. Furthermore, matrix metalloproteases (MMPs) and tissue-specific inhibitors of metalloproteases (TIMPs) are crucial for matrix remodelling processes that occur during regeneration of bone and other tissues. This study has therefore investigated whether MMP activity affects mesenchymal stem cell (

Bone defect treatments can be augmented by mesenchymal stem cell (MSC) based therapies. MSC interaction with the extracellular matrix (ECM) of the surrounding tissue regulates their functional behavior. Understanding of these specific regulatory mechanisms is essential for the therapeutic stimulation of MSC in vivo. However, these interactions are presently only partially understood. This study examined in parallel, for the first time, the effects on the functional behavior of MSCs of 13 ECM components from bone, cartilage and hematoma compared to a control protein, and hence draws conclusions for rational biomaterial design. ECM components specifically modulated MSC adhesion, migration, proliferation, and osteogenic differentiation, for example, fibronectin facilitated migration, adhesion, and proliferation, but not osteogenic differentiation, whereas fibrinogen enhanced adhesion and proliferation, but not migration. Subsequently, the integrin expression pattern of MSCs was determined and related to the cell behavior on specific ECM components. Finally, on this basis, peptide sequences are reported for the potential stimulation of MSC functions. Based on the results of this study, ECM component coatings could be designed to specifically guide cell functions.

Introduction: Intervertebral disc (IVD) degeneration is often associated with low back pain and radiating leg pain. The purpose of this study is to develop a reproducible and standardized preclinical model of painful lumbar IVD degeneration by evaluation of structural and behavioral changes in response to IVD injury with increasing needle sizes. This model can be used to develop new therapies for IVD degeneration.Methods: Forty-five female Sprague Dawley rats underwent anterior lumbar disc needle puncture at levels L4-5 and L5-6 under fluoroscopic guidance. Animals were randomly assigned to four different experimental groups: needle sizes of 18 Gauge (G), 21G, 23G, and sham control. To monitor the progression of IVD degeneration and pain, the following methods were employed: μMRI, qRT-PCR, histology, and biobehavioral analysis.Results: T1-and T2-weighted μMRI analysis showed a correlation between the degree of IVD degeneration and needle diameter, with the most severe degeneration in the 18G group. mRNA expression of markers for IVD degeneration markers were dysregulated in the 18G and 21G groups, while pro-nociceptive markers were increased in the 18G group only. Hematoxylin and Eosin (H&E) and Alcian Blue/ Picrosirius Red staining confirmed the most pronounced IVD degeneration in the 18G group. Randall-Selitto and von Frey tests showed increased hindpaw sensitivity in the 18G group. Conclusion:Our findings demonstrate that anterior disc injury with an 18G needle creates severe IVD degeneration and mechanical hypersensitivity, while the 21G needle results in moderate degeneration with no increased pain sensitivity. Therefore, needle sizes should be selected depending on the desired phenotype for the pre-clinical model.

Angiogenesis is essential to tissue reconstitution, is sensitive to mechanical stresses, and currently represents one of the major challenges in tissue engineering. The pro-angiogenic matrix metalloprotease-2 (MMP-2) is upregulated in mechanically loaded mesenchymal stem cells (MSCs). Therefore, MMP-2 may provide a regulating link between angiogenesis and the surrounding mechanical conditions. This study aimed to modulate MMP-2 levels by mechanical loading of MSCs embedded in a three-dimensional matrix as well as to investigate the mechanism of MMP-2 regulation along with its contribution to angiogenesis stimulation. MMP-2-inducing conditions (30% compression, 1 Hz, 72 h) were defined after varying loading parameters. Addition of the Golgi-disturbing agent Brefeldin A suppressed this mechanical upregulation of MMP-2. Analysis of enzymatic activities demonstrated an enhancement of pro-MMP-2, mature MMP-2, and tissue inhibitor of metalloproteases-2. Further, mechano-regulation of MMP-14 and mature MMP-2 was dependent upon the activity of furin, a proprotein processing endoprotease. Angiogenesis was stimulated by conditioned media from MSCs loaded at inducing conditions. This augmentation of angiogenesis was hindered by inhibition of pro-MMP-2 and mature MMP-2. In conclusion, mechanical stimulation of MSCs in a three-dimensional matrix induces pro-MMP-2 secretion and MMP-2 activation, potentially via the activation complex consisting of MMP-2/-14/tissue inhibitor of metalloproteases-2. Mechano-regulated pro-MMP-2 and mature MMP-2 seem to contribute to angiogenesis stimulation. Thus, an application of these loading parameters could augment vascularization of tissue-engineered constructs based on the described MMP-2-dependent mechanism.

BackgroundIntervertebral disc (IVD) degeneration is a common cause of lower back pain, which carries substantial morbidity and economic cost. Omega-3 fatty acids (n-3 FA) are known to reduce inflammatory processes with a relatively benign side effect profile. This study aimed to investigate the effect of n-3 FA supplementation on IVD degeneration.Material/MethodsTwo non-contiguous lumbar discs of 12 Sprague Dawley rats were needle-punctured to induce disc degeneration. Post-surgery, rats were randomly assigned to either a daily n-3 FA diet (530 mg/kg/day of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in a 2: 1 ratio, administered in sucrose solution) or control diet (sucrose solution only), which was given for the duration of the study. After 1 month, blood serum arachidonic acid/eicosapentaenoic acid (AA/EPA) ratios were analyzed. After 2 months, micro-MRI (magnetic resonance imaging) analysis and histological staining of disc explants were performed to analyze the IVD.ResultsA reduction of blood AA/EPA ratios from 40 to 20 was demonstrated after 1 month of daily supplementation with n-3 FA. Micro-MRI analysis showed an injury-induced reduction of IVD hydration, which was attenuated in rats receiving n-3 FA. Histological evaluation demonstrated the destruction of nucleus pulposus tissue in response to needle puncture injury, which was less severe in the n-3 FA diet group.ConclusionsThe results of this study suggest that n-3 FA dietary supplementation reduces systemic inflammation by lowering AA/EPA ratios in blood serum and has potential protective effects on the progression of spinal disc degeneration, as demonstrated by reduced needle injury-induced dehydration of intervertebral discs and reduced histological signs of IVD degeneration.

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Background: In vitro studies using nucleus pulposus (NP) cells are commonly used to investigate disc cell biology and pathogenesis, or to aid in the development of new therapies. However, lab-to-lab variability jeopardizes the much-needed progress in the field. Here, an international group of spine scientists collaborated to standardize extraction and expansion techniques for NP cells to reduce variability, improve comparability between labs and improve utilization of funding and resources. Methods:The most commonly applied methods for NP cell extraction, expansion, and re-differentiation were identified using a questionnaire to research groups worldwide. NP cell extraction methods from rat, rabbit, pig, dog, cow, and human NP tissue were experimentally assessed. Expansion and re-differentiation media and techniques were also investigated.