Controlled Delivery of Transforming Growth Factor β1 [beta 1] by Self-Assembling Peptide Hydrogels Induces Chondrogenesis of Bone Marrow Stromal Cells and Modulates Smad2/3 Signaling

Self-assembling peptide hydrogels were modified to deliver transforming growth factor b1 [beta 1](TGF-b1)[TGF beta 1] to encapsulated bone-marrow-derived stromal cells (BMSCs) for cartilage tissue engineering applications using two different approaches: (i) biotin-streptavidin tethering; (ii) adsorption to the peptide scaffold. Initial studies to determine the duration of TGF-b1 [TGF beta 1] medium supplementation necessary to stimulate chondrogenesis showed that 4 days of transient soluble TGF-b1 [TGF beta 1] to newborn bovine BMSCs resulted in 10-fold higher proteoglycan accumulation than TGF-b1-free [TGF beta 1 free]culture after 3 weeks. Subsequently, BMSC-seeded peptide hydrogels with either tethered TGF-b1 [TGF beta 1] (Teth-TGF) or adsorbed TGF-b1 [TGF beta 1] (Ads-TGF) were cultured in the TGF-b1-free [TGF beta 1 free] medium, and chondrogenesis was compared to that for BMSCs encapsulated in unmodified peptide hydrogels, both with and without soluble TGF-b1 [TGF beta 1] medium supplementation. Ads-TGF peptide hydrogels stimulated chondrogenesis of BMSCs as demonstrated by cell proliferation and cartilage-like extracellular matrix accumulation, whereas Teth- TGF did not stimulate chondrogenesis. In parallel experiments, TGF-b1 [TGF beta 1] adsorbed to agarose hydrogels stimulated comparable chondrogenesis. Full-length aggrecan was produced by BMSCs in response to Ads-TGF in both peptide and agarose hydrogels, whereas medium-delivered TGF-b1 [TGF beta 1] stimulated catabolic aggrecan cleavage product formation in agarose but not peptide scaffolds. Smad2/3 was transiently phosphorylated in response to Ads-TGF but not Teth-TGF, whereas medium-delivered TGF-b1 [TGF beta 1] produced sustained signaling, suggesting that dose and signal duration are potentially important for minimizing aggrecan cleavage product formation. Robustness of this technology for use in multiple species and ages was demonstrated by effective chondrogenic stimulation of adult equine BMSCs, an important translational model used before the initiation of human clinical studies.National Institutes of Health (U.S.) ( (NIH EB003805) (NIH AR33236) (NIH AR45779)National Institutes of Health (U.S.). Molecular, Cell, and Tissue Biomechanics Training Grant FellowshipArthritis Foundatio

Reduction of liver fibrosis by rationally designed macromolecular telmisartan prodrugs

At present there are no drugs for the treatment of chronic liver fibrosis that have been approved by the Food and Drug Administration of the United States. Telmisartan, a small-molecule antihypertensive drug, displays antifibrotic activity, but its clinical use is limited because it causes systemic hypotension. Here, we report the scalable and convergent synthesis of macromolecular telmisartan prodrugs optimized for preferential release in diseased liver tissue. We have optimized the release of active telmisartan in fibrotic liver to be depot-like (that is, a constant therapeutic concentration) through the molecular design of telmisartan brush-arm star polymers, and show that these lead to improved efficacy and to the avoidance of dose-limiting hypotension in both metabolically and chemically induced mouse models of hepatic fibrosis, as determined by histopathology, enzyme levels in the liver, intact-tissue protein markers, hepatocyte necrosis protection and gene-expression analyses. In rats and dogs, the prodrugs are retained long term in liver tissue, and have a well-tolerated safety profile. Our findings support the further development of telmisartan prodrugs that enable infrequent dosing in the treatment of liver fibrosis.National Institutes of Health (U.S.) (Grant 1R01CA220468-01)National Institutes of Health (U.S.) (Fellowship 1F32EB023101

Design of BET Inhibitor Prodrugs with Superior Efficacy and Devoid of Systemic Toxicities

Prodrugs engineered for preferential activation in diseased versus normal tissues offer immense potential to improve the therapeutic index of preclinical and clinical-stage active pharmaceutical ingredients that either cannot be developed otherwise or whose efficacy or tolerability it is highly desirable to improve. Such approaches, however, often suffer from trial-and-error design, precluding predictive design and optimization. Here, using BET bromodomain inhibitors (BETi)—a class of epigenetic regulators with proven anti-cancer activity but clinical development hindered by systemic adverse effects–– we introduce a platform that overcomes these challenges. Through tuning of traceless linkers appended to a “brush prodrug” scaffold, we demonstrate that it is possible to correlate in vitro prodrug activation kinetics with in vivo tumor pharmacokinetics, leading to novel BETi prodrugs with enhanced anti-tumor efficacy and devoid of dose-limiting toxicities. This work has immediate clinical implications, introducing principles for the predictive design of prodrugs and potentially overcoming hurdles in drug development. </div