Effect of dose and release rate of CTGF and TGFß3 on avascular meniscus healing.

Meniscus tears in the avascular region rarely functionally heal due to poor intrinsic healing capacity, frequently resulting in tear propagation, followed by meniscus deterioration. Recently, we have reported that time-controlled application of connective tissue growth factor (CTGF) and transforming tissue growth factor ß3 (TGFß3) significantly improved healing of avascular meniscus tears by inducing recruitment and step-wise fibrocartilaginous differentiation of mesenchymal stem/progenitor cells (MSCs). In this study, we investigated effects of the dose of CTGF and the release rate of TGFß3 on avascular meniscus healing in our existing explant model. Our hypothesis was that dose and release rate of CTGF and TGFß3 are contributing factors for functional outcome in avascular meniscus healing by stem cell recruitment. Low (100 ng/ml) and high (1,000 ng/ml) doses of CTGF as well as fast (0.46 ± 0.2 ng/day) and slow (0.29 ± 0.1 ng/day) release rates of TGFß3 were applied to our established meniscus explant model for meniscus tears in the inner-third avascular region. The release rate of TGFß3 was controlled by varying compositions of poly(lactic-co-glycolic acids) (PLGA) microspheres. The meniscus explants were then cultured for 8 weeks on top of mesenchymal stem/progenitor cells (MSCs). Among the tested combinations, we found that a high CTGF dose and slow TGFß3 release are most effective for integrated healing of avascular meniscus, demonstrating improvements in alignment of collagen fibers, fibrocartilaginous matrix elaboration and mechanical properties. This study may represent an important step toward the development of a regenerative therapy to improve healing of avascular meniscus tears by stem cell recruitment. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1555-1562, 2019.

Dual-delivery of FGF-2/CTGF from Silk Fibroin/PLCL-PEO Coaxial Fibers Enhances MSC Proliferation and Fibrogenesis.

The success of mesenchymal stem cell transplantation is highly dependent on their survival and controlled fate regulation. This study demonstrates that dual-delivery of connective tissue growth factor (CTGF) and fibroblast growth factor 2 (FGF-2) from a core-shell fiber of Silk Fibroin/poly(L-lactic acid-co-ε-caprolactone)-polyethylene oxide (SF/PLCL-PEO) enhanced fibrogenic lineage differentiation of MSCs. The core-shell structure was confirmed by transmission electron microscopy (TEM), fluorescence microscopy and attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. A sequential release of FGF-2 and CTGF was successfully achieved in this manner. FGF-2 plays an important role in stem cell proliferation and, meanwhile when accompanied with CTGF, has a slightly additive effect on fibrogenic differentiation of MSCs, whereas CTGF promotes fibrogenesis and alleviates osteogenesis, chondrogenesis and adipogenesis.

Effect of GFR on plasma N-terminal connective tissue growth factor (CTGF) concentrations.

BACKGROUND: Connective tissue growth factor (CTGF) has a key role in the pathogenesis of renal and cardiac fibrosis. Its amino-terminal fragment (N-CTGF), the predominant form of CTGF detected in plasma, has a molecular weight in the middle molecular range (18 kDa). However, it is unknown whether N-CTGF is a uremic retention solute that accumulates in chronic kidney disease (CKD) due to decreased renal clearance and whether it can be removed by hemodiafiltration. STUDY DESIGN: 4 observational studies in patients and 2 pharmacokinetic studies in rodents. SETTING & PARTICIPANTS: 4 single-center studies. First study (cross-sectional): 88 patients with CKD not receiving kidney replacement therapy. Second study (cross-sectional): 23 patients with end-stage kidney disease undergoing low-flux hemodialysis. Third study: 9 kidney transplant recipients before and 6 months after transplant. Fourth study: 11 low-flux hemodialysis patients and 12 hemodiafiltration patients before and after one dialysis session. PREDICTOR: First, second, and third study: (residual) glomerular filtration rate (GFR). Fourth study: dialysis modality. OUTCOMES & MEASUREMENTS: Plasma (N-)CTGF concentrations, measured by enzyme-linked immunosorbent assay. RESULTS: In patients with CKD, we observed an independent association between plasma CTGF level and estimated GFR (ß = -0.72; P < 0.001). In patients with end-stage kidney disease, plasma CTGF level correlated independently with residual kidney function (ß = -0.55; P = 0.046). Successful kidney transplant resulted in a decrease in plasma CTGF level (P = 0.008) proportional to the increase in estimated GFR. Plasma CTGF was not removed by low-flux hemodialysis, whereas it was decreased by 68% by a single hemodiafiltration session (P < 0.001). Pharmacokinetic studies in nonuremic rodents confirmed that renal clearance is the major elimination route of N-CTGF. LIMITATIONS: Observational studies with limited number of patients. Fourth study: nonrandomized, evaluation of the effect of one session; randomized longitudinal study is warranted. CONCLUSION: Plasma (N-)CTGF is eliminated predominantly by the kidney, accumulates in CKD, and is decreased substantially by a single hemodiafiltration session.

Renal proximal tubular dysfunction is a major determinant of urinary connective tissue growth factor excretion.

Connective tissue growth factor (CTGF) plays a key role in renal fibrosis. Urinary CTGF is elevated in various renal diseases and may have biomarker potential. However, it is unknown which processes contribute to elevated urinary CTGF levels. Thus far, urinary CTGF was considered to reflect renal expression. We investigated how tubular dysfunction affects urinary CTGF levels. To study this, we administered recombinant CTGF intravenously to rodents. We used both full-length CTGF and the NH(2)-terminal fragment, since the NH(2)-fragment is the predominant form detected in urine. Renal CTGF extraction, determined by simultaneous arterial and renal vein sampling, was 18 +/- 3% for full-length CTGF and 21 +/- 1% for the NH(2)-fragment. Fractional excretion was very low for both CTGFs (0.02 +/- 0.006% and 0.10 +/- 0.02%, respectively), indicating that >99% of the extracted CTGF was metabolized by the kidney. Immunohistochemistry revealed extensive proximal tubular uptake of CTGF in apical endocytic vesicles and colocalization with megalin. Urinary CTGF was elevated in megalin- and cubilin-deficient mice but not in cubilin-deficient mice. Inhibition of tubular reabsorption by Gelofusine reduced renal uptake of CTGF and increased urinary CTGF. In healthy volunteers, Gelofusine also induced an increase of urinary CTGF excretion, comparable to the increase of beta(2)-microglobulin excretion (r = 0.99). Furthermore, urinary CTGF correlated with beta(2)-microglobulin (r = 0.85) in renal disease patients (n = 108), and only beta(2)-microglobulin emerged as an independent determinant of urinary CTGF. Thus filtered CTGF is normally reabsorbed almost completely in proximal tubules via megalin, and elevated urinary CTGF may largely reflect proximal tubular dysfunction.