Multipotent bone marrow cell-seeded polymeric composites drive long-term, definitive urinary bladder tissue regeneration.

To date, there are no efficacious translational solutions for end-stage urinary bladder dysfunction. Current surgical strategies, including urinary diversion and bladder augmentation enterocystoplasty (BAE), utilize autologous intestinal segments (e.g. ileum) to increase bladder capacity to protect renal function. Considered the standard of care, BAE is fraught with numerous short- and long-term clinical complications. Previous clinical trials employing tissue engineering approaches for bladder tissue regeneration have also been unable to translate bench-top findings into clinical practice. Major obstacles still persist that need to be overcome in order to advance tissue-engineered products into the clinical arena. These include scaffold/bladder incongruencies, the acquisition and utility of appropriate cells for anatomic and physiologic tissue recapitulation, and the choice of an appropriate animal model for testing. In this study, we demonstrate that the elastomeric, bladder biomechanocompatible poly(1,8-octamethylene-citrate-co-octanol) (PRS; synthetic) scaffold coseeded with autologous bone marrow-derived mesenchymal stem cells and CD34+ hematopoietic stem/progenitor cells support robust long-term, functional bladder tissue regeneration within the context of a clinically relevant baboon bladder augmentation model simulating bladder trauma. Partially cystectomized baboons were independently augmented with either autologous ileum or stem-cell-seeded small-intestinal submucosa (SIS; a commercially available biological scaffold) or PRS grafts. Stem-cell synergism promoted functional trilayer bladder tissue regeneration, including whole-graft neurovascularization, in both cell-seeded grafts. However, PRS-augmented animals demonstrated fewer clinical complications and more advantageous tissue characterization metrics compared to ileum and SIS-augmented animals. Two-year study data demonstrate that PRS/stem-cell-seeded grafts drive bladder tissue regeneration and are a suitable alternative to BAE.

Advances Toward Engineering Functionally Mature Human Pluripotent Stem Cell-Derived ß Cells.

Human stem cell-derived ß (SC-ß) cells have the potential to revolutionize diabetes treatment through disease modeling, drug screening, and cellular therapy. SC-ß cells are likely to represent an early clinical translation of differentiated human pluripotent stem cells (hPSC). In 2014, two groups generated the first in vitro-differentiated glucose-responsive SC-ß cells, but their functional maturation at the time was low. This review will discuss recent advances in the engineering of SC-ß cells to understand and improve SC-ß cell differentiation and functional maturation, particularly new differentiation strategies achieving dynamic glucose-responsive insulin secretion with rapid correction to normoglycemia when transplanted into diabetic mice.

SIX2 Regulates Human ß Cell Differentiation from Stem Cells and Functional Maturation In Vitro.

Generation of insulin-secreting ß cells in vitro is a promising approach for diabetes cell therapy. Human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) are differentiated to ß cells (SC-ß cells) and mature to undergo glucose-stimulated insulin secretion, but molecular regulation of this defining ß cell phenotype is unknown. Here, we show that maturation of SC-ß cells is regulated by the transcription factor SIX2. Knockdown (KD) or knockout (KO) of SIX2 in SC-ß cells drastically limits glucose-stimulated insulin secretion in both static and dynamic assays, along with the upstream processes of cytoplasmic calcium flux and mitochondrial respiration. Furthermore, SIX2 regulates the expression of genes associated with these key ß cell processes, and its expression is restricted to endocrine cells. Our results demonstrate that expression of SIX2 influences the generation of human SC-ß cells in vitro.

Acquisition of Dynamic Function in Human Stem Cell-Derived ß Cells.

Recent advances in human pluripotent stem cell (hPSC) differentiation protocols have generated insulin-producing cells resembling pancreatic ß cells. While these stem cell-derived ß (SC-ß) cells are capable of undergoing glucose-stimulated insulin secretion (GSIS), insulin secretion per cell remains low compared with islets and cells lack dynamic insulin release. Herein, we report a differentiation strategy focused on modulating transforming growth factor ß (TGF-ß) signaling, controlling cellular cluster size, and using an enriched serum-free media to generate SC-ß cells that express ß cell markers and undergo GSIS with first- and second-phase dynamic insulin secretion. Transplantation of these cells into mice greatly improves glucose tolerance. These results reveal that specific time frames for inhibiting and permitting TGF-ß signaling are required during SC-ß cell differentiation to achieve dynamic function. The capacity of these cells to undergo GSIS with dynamic insulin release makes them a promising cell source for diabetes cellular therapy.

Tumor-on-a-chip platform to investigate progression and drug sensitivity in cell lines and patient-derived organoids.

Most cancer treatment strategies target cell proliferation, angiogenesis, migration, and intravasation of tumor cells in an attempt to limit tumor growth and metastasis. An in vitro platform to assess tumor progression and drug sensitivity could provide avenues to enhance our understanding of tumor metastasis as well as precision medicine. We present a microfluidic platform that mimics biological mass transport near the arterial end of a capillary in the tumor microenvironment. A central feature is a quiescent perfused 3D microvascular network created prior to loading tumor cells or patient-derived tumor organoids in an adjacent compartment. The physiological delivery of nutrients and/or drugs to the tumor then occurs through the vascular network. We demonstrate the culture, growth, and treatment of tumor cell lines and patient-derived breast cancer organoids. The platform provides the opportunity to simultaneously and dynamically observe hallmark features of tumor progression including cell proliferation, angiogenesis, cell migration, and tumor cell intravasation. Additionally, primary breast tumor organoids are viable in the device for several weeks and induce robust sprouting angiogenesis. Finally, we demonstrate the feasibility of our platform for drug discovery and personalized medicine by analyzing the response to chemo- and anti-angiogenic therapy. Precision medicine-based cancer treatments can only be realized if individual tumors can be rapidly assessed for therapeutic sensitivity in a clinically relevant timeframe (⪅14 days). Our platform indicates that this goal can be achieved and provides compelling opportunities to advance precision medicine for cancer.