High-throughput and label-free isolation of senescent murine mesenchymal stem cells

The Matrix Protein Tropoelastin Prolongs Mesenchymal Stromal Cell Vitality and Delays Senescence During Replicative Aging

Cellular senescence leads to the functional decline of regenerative cells such as mesenchymal stromal/stem cells (MSCs), which gives rise to chronic conditions and contributes to poor cell therapy outcomes. Aging tissues are associated with extracellular matrix (ECM) dysregulation, including loss of elastin. However, the role of the ECM in modulating senescence is underexplored. In this work, it is shown that tropoelastin, the soluble elastin precursor, is not only a marker of young MSCs but also actively preserves cell fitness and delays senescence during replicative aging. MSCs briefly exposed to tropoelastin exhibit upregulation of proliferative genes and concurrent downregulation of senescence genes. The seno-protective benefits of tropoelastin persist during continuous, long-term MSC culture, and significantly extend the MSC replicative lifespan. Tropoelastin-expanded MSCs further maintain youth-associated phenotype and function compared to age-matched controls, including preserved clonogenic potential, minimal senescence-associated beta-galactosidase activity, maintained cell sizes, reduced expression of senescence markers, suppressed secretion of senescence-associated factors, and increased production of youth-associated proteins. This work points to the utility of exogenously-supplemented tropoelastin for manufacturing MSCs that robustly maintain regenerative potential with age. It further reveals the active role of classical structural ECM proteins in driving cellular age-associated fitness, potentially leading to future interventions for aging-related pathologies.

Scaling up stem cell production: harnessing the potential of microfluidic devices

Stem cells are specialised cells characterised by their unique ability to both self-renew and transform into a wide array of specialised cell types. The widespread interest in stem cells for regenerative medicine and cultivated meat has led to a significant demand for these cells in both research and practical applications. Despite the growing need for stem cell manufacturing, the industry faces significant obstacles, including high costs for equipment and maintenance, complicated operation, and low product quality and yield. Microfluidic technology presents a promising solution to the abovementioned challenges. As an innovative approach for manipulating liquids and cells within microchannels, microfluidics offers a plethora of advantages at an industrial scale. These benefits encompass low setup costs, ease of operation and multiplexing, minimal energy consumption, and the added advantage of being labour-free. This review presents a thorough examination of the prominent microfluidic technologies employed in stem cell research and explores their promising applications in the burgeoning stem cell industry. It thoroughly examines how microfluidics can enhance cell harvesting from tissue samples, facilitate mixing and cryopreservation, streamline microcarrier production, and efficiently conduct cell separation, purification, washing, and final cell formulation post-culture.

Stress-induced senescence in mesenchymal stem cells: Triggers, hallmarks, and current rejuvenation approaches

Mesenchymal stem cells (MSCs) have emerged as promising cell-based therapies in the treatment of degenerative and inflammatory conditions. However, despite accumulating evidence of the breadth of MSC functional potency, their broad clinical translation is hampered by inconsistencies in therapeutic efficacy, which is at least partly due to the phenotypic and functional heterogeneity of MSC populations as they progress towards senescence in vitro. MSC senescence, a natural response to aging and stress, gives rise to altered cellular responses and functional decline. This review describes the key regenerative properties of MSCs; summarises the main triggers, mechanisms, and consequences of MSC senescence; and discusses current cellular and extracellular strategies to delay the onset or progression of senescence, or to rejuvenate biological functions lost to senescence.

Developing a far-red fluorogenic beta-galactosidase probe for senescent cell imaging and photoablation

A methylene blue (MB)-based beta-galactosidase (β-gal) activatable molecule, Gal-MB, was developed for senescence imaging and light-triggered senolysis. When in contact with LacZ β-gal or senescence-associated β-gal (SA-β-gal), the photoinsensitive Gal-MB becomes fluorescent. Gal-MB also offered selective phototoxicity toward LacZ β-gal expressing cells and drug-induced senescent cells, which express SA-β-gal, after light illumination at 665 nm.

A methylene blue (MB)-based beta-galactosidase (β-gal) activatable molecule, Gal-MB, was developed for senescence imaging and light-triggered senolysis.

Continuous Particle Separation Driven by 3D Ag-PDMS Electrodes with Dielectric Electrophoretic Force Coupled with Inertia Force

Cell separation has become @important in biological and medical applications. Dielectrophoresis (DEP) is widely used due to the advantages it offers, such as the lack of a requirement for biological markers and the fact that it involves no damage to cells or particles. This study aimed to report a novel approach combining 3D sidewall electrodes and contraction/expansion (CEA) structures to separate three kinds of particles with different sizes or dielectric properties continuously. The separation was achieved through the interaction between electrophoretic forces and inertia forces. The CEA channel was capable of sorting particles with different sizes due to inertial forces, and also enhanced the nonuniformity of the electric field. The 3D electrodes generated a non-uniform electric field at the same height as the channels, which increased the action range of the DEP force. Finite element simulations using the commercial software, COMSOL Multiphysics 5.4, were performed to determine the flow field distributions, electric field distributions, and particle trajectories. The separation experiments were assessed by separating 4 µm polystyrene (PS) particles from 20 µm PS particles at different flow rates by experiencing positive and negative DEP. Subsequently, the sorting performances of the 4 µm PS particles, 20 µm PS particles, and 4 µm silica particles with different solution conductivities were observed. Both the numerical simulations and the practical particle separation displayed high separating efficiency (separation of 4 µm PS particles, 94.2%; separation of 20 µm PS particles, 92.1%; separation of 4 µm Silica particles, 95.3%). The proposed approach is expected to open a new approach to cell sorting and separating.

Emerging microfluidics-enabled platforms for osteoarthritis management: from benchtop to bedside

Osteoarthritis (OA) is a prevalent debilitating age-related joint degenerative disease. It is a leading cause of pain and functional disability in older adults. Unfortunately, there is no cure for OA once the damage is established. Therefore, it promotes an urgent need for early detection and intervention of OA. Theranostics, combining therapy and diagnosis, emerges as a promising approach for OA management. However, OA theranostics is still in its infancy. Three fundamental needs have to be firstly fulfilled: i) a reliable OA model for disease pathogenesis investigation and drug screening, ii) an effective and precise diagnostic platform, and iii) an advanced fabrication approach for drug delivery and therapy. Meanwhile, microfluidics emerges as a versatile technology to address each of the needs and eventually boost the development of OA theranostics. Therefore, this review focuses on the applications of microfluidics, from benchtop to bedside, for OA modelling and drug screening, early diagnosis, and clinical therapy. We first introduce the basic pathophysiology of OA and point out the major unfilled research gaps in current OA management including lack of disease modelling and drug screening platforms, early diagnostic modalities and disease-modifying drugs and delivery approaches. Accordingly, we then summarize the state-of-the-art microfluidics technology for OA management from in vitro modelling and diagnosis to therapy. Given the existing promising results, we further discuss the future development of microfluidic platforms towards clinical translation at the crossroad of engineering and biomedicine.