Mesenchymal and induced pluripotent stem cell-based therapeutics: a comparison

Expansion of induced pluripotent stem cells under consideration of bioengineering aspects: part 2

The manufacturing of allogeneic cell therapeutics based on human-induced pluripotent stem cells (hiPSCs) holds considerable potential to revolutionize the accessibility and affordability of modern healthcare. However, achieving the cell yields necessary to ensure robust production hinges on identifying suitable and scalable single-use (SU) bioreactor systems. While specific stirred SU bioreactor types have demonstrated proficiency in supporting hiPSC expansion at L-scale, others, notably instrumented SU multiplate and fixed-bed bioreactors, remain relatively unexplored. By characterizing these bioreactors using both computational fluid dynamics and experimental bioengineering methods, operating ranges were identified for the Xpansion® 10 and Ascent™ 1 m2 bioreactors in which satisfactory hiPSC expansion under serum-free conditions was achieved. These operating ranges were shown not only to effectively limit cell exposure to wall shear stress but also facilitated sufficient oxygen transfer and mixing. Through their application, almost 5 × 109 viable cells could be produced within 5 days, achieving expansion factors of up to 35 without discernable impact on cell viability, identity, or differentiation potential. Key Points •Bioengineering characterizations allowed the identification of operating ranges that supported satisfactory hiPSC expansion •Both the Xpansion® 10 multiplate and Ascent™ 1 m2 fixed-bed reactor accommodated the production of almost 5 × 109 viable cells within 5 days •Exposing the hiPSCs to a median wall shear stress of up to 8.2 × 10-5 N cm-2 did not impair quality.

Spheroid trilineage differentiation model of primary mesenchymal stem/stromal cells under hypoxia and serum-free culture conditions

Due to their unique properties, human mesenchymal stem/stromal cells (MSCs) possess tremendous potential in regenerative medicine, particularly in cell-based therapies where the multipotency and immunomodulatory characteristics of MSCs can be leveraged to address a variety of disease states. Although MSC-based cell therapeutics have emerged as one of the most promising medical treatments, the clinical translation is hampered by the variability of MSC-based cellular products caused by tissue source-specific differences and the lack of physiological cell culture approaches that closely mimic the human cellular microenvironment. In this study, a model for trilineage differentiation of primary adipose-, bone marrow-, and umbilical cord-derived MSCs into adipocytes, chondrocytes and osteoblasts was established and characterized. Differentiation was performed in spheroid culture, using hypoxic conditions and serum-free and antibiotics-free medium. This platform was characterized for spheroid diameter and trilineage differentiation capacity reflecting functionality of differentiated cells, as indicated by lineage-specific extracellular matrix (ECM) accumulation and expression of distinct secreted markers. The presented model shows spheroid growth during the course of differentiation and successfully supports trilineage differentiation for MSCs from almost all tissue sources except for osteogenesis of umbilical cord-derived MSCs. These findings indicate that this platform provides a suitable and favorable environment for trilineage differentiation of MSCs from various tissue sources. Therefore, it poses a promising model to generate highly relevant biological data urgently required for clinical translation and therefore might be used in the future to generate in vitro microtissues, building blocks for tissue engineering or as disease models.

Synthetic Gene Circuits for Regulation of Next-Generation Cell-Based Therapeutics

Arming human cells with synthetic gene circuits enables to expand their capacity to execute superior sensing and response actions, offering tremendous potential for innovative cellular therapeutics. This can be achieved by assembling components from an ever-expanding molecular toolkit, incorporating switches based on transcriptional, translational, or post-translational control mechanisms. This review provides examples from the three classes of switches, and discusses their advantages and limitations to regulate the activity of therapeutic cells in vivo. Genetic switches designed to recognize internal disease-associated signals often encode intricate actuation programs that orchestrate a reduction in the sensed signal, establishing a closed-loop architecture. Conversely, switches engineered to detect external molecular or physical cues operate in an open-loop fashion, switching on or off upon signal exposure. The integration of such synthetic gene circuits into the next generation of chimeric antigen receptor T-cells is already enabling precise calibration of immune responses in terms of magnitude and timing, thereby improving the potency and safety of therapeutic cells. Furthermore, pre-clinical engineered cells targeting other chronic diseases are gathering increasing attention, and this review discusses the path forward for achieving clinical success. With synthetic biology at the forefront, cellular therapeutics holds great promise for groundbreaking treatments.