Topological defects in self-assembled patterns of mesenchymal stromal cells in vitro are predictive attributes of condensation and chondrogenesis.

Mesenchymal stromal cells (MSCs) are promising therapeutic agents for cartilage regeneration, including the potential of cells to promote chondrogenesis in vivo. However, process development and regulatory approval of MSCs as cell therapy products benefit from facile in vitro approaches that can predict potency for a given production run. Current standard in vitro approaches include a 21 day 3D differentiation assay followed by quantification of cartilage matrix proteins.

Dissolvable Gelatin-Based Microcarriers Generated through Droplet Microfluidics for Expansion and Culture of Mesenchymal Stromal Cells.

Microcarriers are synthetic particles used in bioreactor-based cell manufacturing of anchorage-dependent cells to promote proliferation at efficient physical volumes, mainly by increasing the surface area-to-volume ratio. Mesenchymal stromal cells (MSCs) are adherent cells that are used for numerous clinical trials of autologous and allogeneic cell therapy, thus requiring avenues for large-scale cell production at efficiently low volumes and cost. Here, a dissolvable gelatin-based microcarrier is developed for MSC expansion.

Single-cell assays using integrated continuous-flow microfluidics.

The recent maturation of continuous-flow microfluidic technologies has coincided with transformative new methods to profile single cells, including their genetic types, protein expression and enzyme activities. Continuous-flow high-throughput single-cell screening and sorting can reveal relationships across cellular phenotypes (e.g.

Ultrafast Single-Cell Level Enzymatic Tumor Profiling.

In the context of tumor analysis, the implementation of precision medicine requires on-time clinical measurements, which requires rapid large-scale single-cell screening that obtains cell population distributions and functions in tumors to determine disease progression for therapeutics. In this study, a high-throughput screening (HTS) platform integrating optical fluorescence detectors and a computational method was developed as a droplet-based microfluidic flow cytometer (Droplet-μFC) to comprehensively analyze multiple proteolytic activities of a patient-derived tumor (with ∼0.5-2 M cells) at single-cell resolution within 2 h.

Single cell multiplexed assay for proteolytic activity using droplet microfluidics.

Cellular enzymes interact in a post-translationally regulated fashion to govern individual cell behaviors, yet current platform technologies are limited in their ability to measure multiple enzyme activities simultaneously in single cells. Here, we developed multi-color Förster resonance energy transfer (FRET)-based enzymatic substrates and use them in a microfluidics platform to simultaneously measure multiple specific protease activities from water-in-oil droplets that contain single cells. By integrating the microfluidic platform with a computational analytical method, Proteolytic Activity Matrix Analysis (PrAMA), we are able to infer six different protease activity signals from individual cells in a high throughput manner (~100 cells/experimental run).

Low-volume multiplexed proteolytic activity assay and inhibitor analysis through a pico-injector array.

Secreted active proteases, from families of enzymes such as matrix metalloproteinases (MMPs) and ADAMs (a disintegrin and metalloproteinases), participate in diverse pathological processes. To simultaneously measure multiple specific protease activities, a series of parallel enzyme reactions combined with a series of inhibitor analyses for proteolytic activity matrix analysis (PrAMA) are essential but limited due to the sample quantity requirements and the complexity of performing multiple reactions. To address these issues, we developed a pico-injector array to generate 72 different reactions in picoliter-volume droplets by controlling the sequence of combinational injections, which allowed simultaneous recording of a wide range of multiple enzyme reactions and measurement of inhibitor effects using small sample volumes (~10 μL).