Label-free mesenchymal stem cell enrichment from bone marrow samples by inertial microfluidics

Abstract

Isolation of pure populations of mesenchymal stem cells from bone marrow aspirate is a critical need in regenerative medicine such as orthopedic and cartilage reconstruction with important clinical and therapeutic implications. Currently available stem cell isolation systems mainly rely on intrusive immuno-labeling techniques. Mesenchymal stem cells in bone marrow samples are typically larger than other cells, which can be used as a distinctive biophysical cue for non-invasive isolation. In this work, a spiral-shaped inertial microfluidic sorter was developed to isolate mesenchymal stem cells from mouse bone marrow samples with minimal sample preparation steps. To characterize the sorting performance, cultured mesenchymal stem cells were spiked into tissue-digested mouse bone marrow cells. At a flow rate of 1.6 mL min⁻¹, an average enrichment of 6.0× and a recovery of 73% were demonstrated. About 3 × 10⁶ tissue-digested bone marrow cells can be processed in 1 minute with a single microfluidic run. The recovered mesenchymal stem cells after microfluidic sorting retained high (>95%) viability and similar immuno-phenotype expressions and multi-potencies in tri-differentiation lineages to unprocessed cells. This rapid, label-free and non-invasive inertial microfluidic sorter has practical applications in target stem cell enrichment in stem cell therapy.