Pushing the limits of microfluidic droplet production efficiency: engineering microchannels with seamlessly implemented 3D inverse colloidal crystals.

Although droplet microfluidics has been studied for the past two decades, its applications are still limited due to the low productivity of microdroplets resulting from the low integration of planar microchannel structures. In this study, a microfluidic system implementing inverse colloidal crystals (ICCs), a spongious matrix with regularly and densely formed three-dimensional (3D) interconnected micropores, was developed to significantly increase the throughput of microdroplet generation. A new bottom-up microfabrication technique was developed to seamlessly integrate the ICCs into planar microchannels by accumulating non-crosslinked spherical PMMA microparticles as sacrificial porogens in a selective area of a mold and later dissolving them. We have demonstrated that the densely arranged micropores on the spongious ICC of the microchannel function as massively parallel micronozzles, enabling droplet formation on the order of >10 kHz. Droplet size could be adjusted by flow conditions, fluid properties, and micropore size, and biopolymer particles composed of polysaccharides and proteins were produced. By further parallelization of the unit structures, droplet formation on the order of >100 kHz was achieved. The presented approach is an upgrade of the existing droplet microfluidics concept, not only in terms of its high throughput, but also in terms of ease of fabrication and operation.

Systemic Supplementation of Collagen VI by Neonatal Transplantation of iPSC-Derived MSCs Improves Histological Phenotype and Function of Col6-Deficient Model Mice.

Collagen VI is distributed in the interstitium and is secreted mainly by mesenchymal stromal cells (MSCs) in skeletal muscle. Mutations in COL6A1-3 genes cause a spectrum of COL6-related myopathies. In this study, we performed a systemic transplantation study of human-induced pluripotent stem cell (iPSC)-derived MSCs (iMSCs) into neonatal immunodeficient COL6-related myopathy model (Col6a1 KO /NSG) mice to validate the therapeutic potential. Engraftment of the donor cells and the resulting rescued collagen VI were observed at the quadriceps and diaphragm after intraperitoneal iMSC transplantation. Transplanted mice showed improvement in pathophysiological characteristics compared with untreated Col6a1 KO /NSG mice. In detail, higher muscle regeneration in the transplanted mice resulted in increased muscle weight and enlarged myofibers. Eight-week-old mice showed increased muscle force and performed better in the grip and rotarod tests. Overall, these findings support the concept that systemic iMSC transplantation can be a therapeutic option for COL6-related myopathies.