Systems for local, sustained release of zoledronic acid as a potential treatment for metastatic bone disease.

Bone pain is the leading cause of morbidity in patients with metastatic cancer. Systemic administration of zoledronic acid (ZA) decreases skeletally-related events in bone cancer patients but is associated with major side effects. This project investigated two biomaterials, poly(methyl methacrylate) (PMMA) bone cement and poly(lactic-co-glycolic acid) (PLGA), for local ZA delivery. Compressive properties of PMMA samples were tested with increased drug loading, and in vitro ZA release profiles from PMMA cylinders and PLGA films were measured over 8 weeks. The activity of ZA eluted from both materials was evaluated on the RAW 264.7 macrophage cell line. PMMA samples released up to only 17% of incorporated drug, whereas PLGA films released over 95%. A burst profile was observed for PMMA, while ZA release from PLGA exhibited a typical triphasic profile. Drug bioactivity remained above 50% for both materials. Local ZA delivery from these materials may be useful in the treatment of metastatic bone cancer.

Energy and enstrophy spectra and fluxes for the inertial-dissipation range of two-dimensional turbulence.

In this paper, using Pao's conjecture [Y.-H. Pao, Phys. Fluids 8, 1063 (1965)10.1063/1.1761356], we derive expressions for the spectra and fluxes of kinetic energy and enstrophy for two-dimensional (2D) forced turbulence that extend beyond the inertial range. In these expressions, the fluxes and the spectra contain additional factors of the exponential form. To validate these model predictions, we perform numerical simulations of 2D turbulence with external force applied at wavenumber band (k_{f},k_{f}+1) in the intermediate range. The numerical results match with the model predictions, except for the energy and enstrophy fluxes for k

The effect of adipose-derived stem cell sheets and CTGF on early flexor tendon healing in a canine model.

Intrasynovial tendon injuries are among the most challenging in orthopedics. Despite significant improvements in operative and rehabilitation methods, functional outcomes continue to be limited by adhesions, gap formation, and rupture. Adhesions result from excessive inflammation, whereas tendon gapping and rupture result from inflammation-induced matrix degradation and insufficient regeneration. Therefore, this study used a combined treatment approach to modulate inflammation with adipose-derived mesenchymal stromal cells (ASCs) while stimulating tendon regeneration with connective tissue growth factor (CTGF). ASCs were applied to the repair surface via cell sheets and CTGF was delivered to the repair center via porous sutures. The effect of the combined treatment was assessed fourteen days after repair in a canine flexor tendon injury model. CTGF, either alone or with ASCs, reduced inflammatory (IL1B and IL6) and matrix degrading (MMP3 and MMP13) gene expression, while increasing anti-inflammatory gene (IL4) expression and collagen synthesis compared to control repairs. The combined treatment was more effective than CTGF treatment alone, reducing the inflammatory IFNG and scar-associated COL3A1 gene expression and increasing CD146+ tendon stem/progenitor cells at the tendon surface and interior along the core suture tracks. Therefore, the combined approach is promising in promoting early flexor tendon healing and worthy of further investigation.

Effect of connective tissue growth factor delivered via porous sutures on the proliferative stage of intrasynovial tendon repair.

Recent growth factor, cell, and scaffold-based experimental interventions for intrasynovial flexor tendon repair have demonstrated therapeutic potential in rodent models. However, these approaches have not achieved consistent functional improvements in large animal trials due to deleterious inflammatory reactions to delivery materials and insufficient induction of targeted biological healing responses. In this study, we achieved porous suture-based sustained delivery of connective tissue growth factor (CTGF) into flexor tendons in a clinically relevant canine model. Repairs with CTGF-laden sutures were mechanically competent and did not show any evidence of adhesions or other negative inflammatory reactions based on histology, gene expression, or proteomics analyses at 14 days following repair. CTGF-laden sutures induced local cellular infiltration and a significant biological response immediately adjacent to the suture, including histological signs of angiogenesis and collagen deposition. There were no evident widespread biological effects throughout the tendon substance. There were significant differences in gene expression of the macrophage marker CD163 and anti-apoptotic factor BCL2L1; however, these differences were not corroborated by proteomics analysis. In summary, this study provided encouraging evidence of sustained delivery of biologically active CTGF from porous sutures without signs of a negative inflammatory reaction. With the development of a safe and effective method for generating a positive local biological response, future studies can explore additional methods for enhancing intrasynovial tendon repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2052-2063, 2018.

Combined Administration of ASCs and BMP-12 Promotes an M2 Macrophage Phenotype and Enhances Tendon Healing.

BACKGROUND: Outcomes after intrasynovial tendon repair are highly variable. An intense inflammatory cascade followed by a delayed healing response can cause adhesion formation and repair-site failure that severely impair the function of repaired digits. No effective remedies exist to fully address these issues. Cell- and growth factor-based therapies have been shown to modulate inflammation and improve cell proliferation and matrix synthesis and therefore are promising treatment approaches for intrasynovial tendon repair. QUESTIONS/PURPOSES: (1) Can autologous adipose-derived mesenchymal stromal cells (ASCs) and recombinant bone morphogenetic protein-12 (rBMP-12) be effectively delivered to an intrasynovial flexor tendon repair without adverse effects? (2) Do autologous ASCs modulate the inflammatory response after intrasynovial tendon injury and repair? (3) Does the combined application of autologous ASCs and rBMP-12 modulate the proliferative and remodeling responses after intrasynovial tendon injury and repair? METHODS: Sixteen 1- to 2-year-old female canines were used in this study. Autologous ASC sheets, with and without rBMP-12, were applied to the surface of sutured flexor tendons. Fourteen days after repair, the effects of treatment were determined using quantitative PCR (six per group) for the expression of genes related to macrophage phenotype or inflammation (IL-4, CD163, VEGF, NOS2, IL-1B, and IFNG), cell proliferation (CCND1), and tendon formation (SCX, TNMD, COL1A1 and COL3A1). Proteomics analysis (four per group) was performed to examine changes in tendon protein abundances. CD146 immunostaining and hematoxylin and eosin staining (four per group) were used to detect tendon stem or progenitor cells and to semiquantitatively evaluate cellularity at the tendon repair; analyses were done blinded to group. RESULTS: Gross inspection and cell tracing showed that autologous ASCs and rBMP-12 were delivered to the flexor tendon repair site without the deleterious effects of adhesion and repair-site gap formation. Quantitative assessment of gene and protein expression showed effects of treatment: ASC-sheet treatment modulated the postrepair inflammatory response and facilitated healing by increasing regenerative M2 macrophages (M2 marker CD204, twofold of normal, p = 0.030), inflammatory inhibitor (prostaglandin reductase 1 [PTRG1], 1.6-fold of normal, p = 0.026), and proteins involved in tendon formation (periostin [POSTN], 1.9-fold of normal, p = 0.035). Consistently, semiquantitative and qualitative evaluations of repaired tissue showed that ASC-sheet treatment reduced mononuclear cell infiltration (12% less than nontreated tendons, p = 0.021) and introduced CD146+ stem or progenitor cells to the repair site. The combined administration of ASCs and rBMP-12 further stimulated M2 macrophages by increasing IL-4 (116-fold of normal, p = 0.002) and led to the increase of M2 effector matrix metalloproteinase-12 involved in matrix remodeling (twofold of normal, p = 0.016) and reduction of a negative regulator of angiogenesis and cell migration (StAR-related lipid transfer domain protein13 [STARD13]; 84% of normal, p = 0.000), thus facilitating the proliferative stage of tendon repair. CONCLUSIONS: ASCs and BMP-12 accelerated the progression of healing in the proliferative stage of tendon repair. The effects of ASCs and BMP-12 on tendon functional recovery should be evaluated in future studies. CLINICAL RELEVANCE: The cell sheet approach is an effective, biocompatible, and surgeon-friendly approach for cell and growth factor delivery during tendon repair. Combined application of ASCs and BMP-12 may accelerate intrasynovial tendon healing while suppressing the adverse inflammatory response.