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IntroductionCell therapy is a rapidly growing area of research for the treatment of osteoarthritis (OA). This work is aimed to investigate the efficacy of intra-articular adipose-derived stromal cell (ASC) injection in the healing process on cartilage, synovial membrane and menisci in an experimental rabbit model.MethodsThe induction of OA was performed surgically through bilateral anterior cruciate ligament transection (ACLT) to achieve eight weeks from ACLT a mild grade of OA. A total of 2 × 106 and 6 × 106 autologous ASCs isolated from inguinal fat, expanded in vitro and suspended in 4% rabbit serum albumin (RSA) were delivered in the hind limbs; 4% RSA was used as the control. Local bio-distribution of the cells was verified by injecting chloro-methyl-benzamido-1,1'-dioctadecyl-3,3,3'3'-tetra-methyl-indo-carbocyanine per-chlorate (CM-Dil) labeled ASCs in the hind limbs. Cartilage and synovial histological sections were scored by Laverty's scoring system to assess the severity of the pathology. Protein expression of some extracellular matrix molecules (collagen I and II), catabolic (metalloproteinase-1 and -3) and inflammatory (tumor necrosis factor- α) markers were detected by immunohistochemistry. Assessments were carried out at 16 and 24 weeks.ResultsLabeled-ASCs were detected unexpectedly in the synovial membrane and medial meniscus but not in cartilage tissue at 3 and 20 days from ASC-treatment. Intra-articular ASC administration decreases OA progression and exerts a healing contribution in the treated animals in comparison to OA and 4% RSA groups.ConclusionsOur data reveal a healing capacity of ASCs in promoting cartilage and menisci repair and attenuating inflammatory events in synovial membrane inhibiting OA progression. On the basis of the local bio-distribution findings, the benefits obtained by ASC treatment could be due to a trophic mechanism of action by the release of growth factors and cytokines.

Platelet-Rich Plasma (PRP) is a low-cost procedure to deliver high concentrations of autologous growth factors (GFs). Platelet activation is a crucial step that might influence the availability of bioactive molecules and therefore tissue healing. Activation of PRP from ten voluntary healthy males was performed by adding 10% of CaCl2, 10% of autologous thrombin, 10% of a mixture of CaCl2 + thrombin, and 10% of collagen type I. Blood derivatives were incubated for 15 and 30 minutes and 1, 2, and 24 hours and samples were evaluated for the release of VEGF, TGF-β1, PDGF-AB, IL-1β, and TNF-α. PRP activated with CaCl2, thrombin, and CaCl2/thrombin formed clots detected from the 15-minute evaluation, whereas in collagen-type-I-activated samples no clot formation was noticed. Collagen type I produced an overall lower GF release. Thrombin, CaCl2/thrombin, and collagen type I activated PRPs showed an immediate release of PDGF and TGF-β 1 that remained stable over time, whereas VEGF showed an increasing trend from 15 minutes up to 24 hours. CaCl2 induced a progressive release of GFs from 15 minutes and increasing up to 24 hours. The method chosen to activate PRP influences both its physical form and the releasate in terms of GF amount and release kinetic.

L-PRP and P-PRP induced distinct effects on human articular chondrocytes in vitro, possibly because of differences in the concentrations of platelets, leukocytes, growth factors, and other bioactive molecules. The identification of the optimal amounts and ratios of these blood components could ideally lead to a formulation more suitable for the treatment of cartilage lesions.

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From the observations, it is possible to demonstrate that Hyaff-11, a hyaluronan-based scaffold, has potential for MSC implantation and that may have application for the treatment of early OA in humans.

Hyaluronan (HA), in the bone marrow stroma, is the major non-protein glycosaminoglycan component of extracellular matrix (ECM) involved in cell positioning, proliferation, differentiation as well as in receptor-mediated changes in gene expression. Repair of bone and regeneration of bone marrow is dependent on ECM, inflammatory factors, like chemokines and degradative factors, like metalloproteinases. We analyzed the interaction between human mesenchymal stem cells (h-MSCs) and a three-dimensional (3-D) HA-based scaffold in vitro. The expression of CXC chemokines/receptors, CXCL8 (IL-8)/CXCR1-2, CXCL10 (IP-10)/CXCR3, CXCL12 (SDF-1)/CXCR4, and CXCL13 (BCA-1)/CXCR5, and metalloproteinases/inhibitors MMP-1, MMP-3, MMP-13/TIMP-1 were evaluated in h-MSCs grown on plastic or on HA-based scaffold by Real-time PCR, ELISA, and immunocytochemical techniques. Moreover, the expression of two HA receptors, CD44 and CD54, was analyzed. We found both at mRNA and protein levels that HA-based scaffold induced the expression of CXCR4, CXCL13, and MMP-3 and downmodulated the expression of CXCL12, CXCR5, MMP-13, and TIMP-1 while HA-based scaffold induced CD54 expression but not CD44. We found that these two HA receptors were directly involved in the modulation of CXCL12, CXCL13, and CXCR5. This study demonstrates a direct action of a 3-D HA-based scaffold, widely used for cartilage and bone repair, in modulating both h-MSCs inflammatory and degradative factors directly involved in the engraftment of specific cell types in a damaged area. Our data clearly demonstrate that HA in this 3-D conformation acts as a signaling molecule for h-MSCs.