Thermoresponsive Cationic Block Copolymer Brushes for Temperature‐Modulated Stem Cell Separation

Abstract

Recently, cell separation methods have become important for preparing cells for transplantation therapy. In this study, a thermoresponsive cationic block copolymer brush is developed as an effective cell separation tool. This brush is prepared on glass surfaces using two steps of activator regenerated by electron transfer–atom transfer radical polymerization (ARGET‐ATRP). The cationic segment is prepared in the first step of the ARGET‐ATRP of N,N‐dimethylaminopropylacrylamide (DMAPAAm). In the second step, the thermoresponsive segment is prepared, attached to the bottom cationic segment, through ARGET‐ATRP with N‐isopropylacrylamide (NIPAAm). The cell adhesion behavior of the prepared thermoresponsive cationic copolymer, PDMAPAAm‐b‐PNIPAAm, brush is observed using umbilical cord‐derived mesenchymal stem cells (UCMSC), fibroblasts, and macrophages. At 37 °C, all three types of cells adhere to the thermoresponsive cationic copolymer brush. Then, by reducing the temperature to 20 °C, the adhered UCMSC are detached from the copolymer brush, whereas the fibroblasts and macrophages remain adhered to the copolymer brush. Using this copolymer brush, UCMSC can be purified from the cell mixture simply by changing the temperature. Therefore, the prepared thermoresponsive cationic copolymer brush is useful as a cell separation tool for the purification of mesenchymal stem cells.

Exogenous Cell Surface Modification with Cell Penetrating Peptide-Conjugated Lipids Causes Spontaneous Cell Adhesion

“…These results indicate that positively charged Tat peptides were immobilized onto the cellular surface by anchoring the PEG-lipids. Since the cellular surface is negatively charged due to the expression of sialic acid and membrane proteins, the zeta potential showed a highly negative value . Although we inserted Tat peptides onto the cellular surface, the total charge of the modified cellular surface was still negative (approximately −25 mV).…”

“…Since the cellular surface is negatively charged due to the expression of sialic acid and membrane proteins, the zeta potential showed a highly negative value. 20 Although we inserted Tat peptides onto the cellular surface, the total charge of the modified cellular surface was still negative (approximately −25 mV). Importantly, we did not observe any cytotoxicity after modification with positively charged Tat peptides due to their cell-penetrating properties.…”

“…Mal-PEG-lipids with different MW PEG chains (5,10,20, and 40 kDa) were synthesized, as described in our previous reports. 14,18 Four different MWs of Mal-PEG (5,10,20, and 40 kDa)-NHS (500, 500, 500, and 500 mg, respectively) were mixed with DPPE (69.2, 34.6, 17.3, and 8.65 mg, respectively) and dichloromethane (4 mL) and then mixed with triethylamine (50 μL). The resulting solutions were reacted for 4 days at room temperature.…”

Terminal cationization of poly(N-isopropylacrylamide) brush surfaces facilitates efficient thermoresponsive control of cell adhesion and detachment

“…In this decade, thermoresponsive cationic brush surfaces have been investigated to develop smart cell separation systems for the purification of target cells (e.g. mesenchymal stem cells) from cell mixture without cell labelling [ 44 , 45 ]. These cell separations are known to be achieved because of the differences between individual cellular properties, including zeta potentials and cell adhesion/detachment behaviors.…”

Thermoresponsive block copolymer brush for temperature-modulated hepatocyte separation

“…67 To improve selectivity, an ionic PNIPAAm copolymer was used; the differences in ionic properties among cell types enable specific cell adhesion on PNIPAAm copolymermodified substrates. 26,[68][69][70] Using this approach, mesenchymal stem cells have been effectively separated. 26,70 In addition, using laminin-coated PNIPAAm modified dishes, cardiomyocytes differentiated from human pluripotent stem cells (hPSCs) were purified from undifferentiated hPSCs because cardiomyocytes selectively detached from the dish because of the relatively weaker adhesive properties compared to those of undifferentiated hPSCs, whereas undifferentiated hPSCs remained on the culture dish because of the relatively stronger adhesive properties compared with those of cardiomyocytes.…”