Sunday, November 24, 2013

Microelectrodes for On-Chip Manipulation of Human Mesenchymal Stem Cells

Amping up Osteogenesis Assays for Drug Discovery

Neuromics and Vitrobiopharma are developing kinetic, differentiation asssays for improving the Drug Discovery process for Osteo-related diseases like Osteoporosis and Osteoarthritis. We have the ability to develop in vivo like assays with quantitative endpoints. The foundation of these assays are potent, easy to culture and cost effective Human Mesenchymal Stem Cells (hMCSCs).

I wanted to share an excellent study using our hMSCs for Osteogenesis Assays: Hsiao, Y.-S., Kuo, C.-W. and Chen, P. (2013), Multifunctional Graphene–PEDOT Microelectrodes for On-Chip Manipulation of Human Mesenchymal Stem Cells. Adv. Funct. Mater., 23: 4649–4656. doi: 10.1002/adfm.201203631. This represents a novel approach for Osteogenesis Assays and illustrates the capabilities of our hMSCs.
Absract: All-solution-processed multifunctional organic bioelectronics composed of reduced graphene oxide (rGO) and dexamethasone 21-phosphate disodium salt (DEX)-loaded poly(3,4-ethylenedioxythiophene) (PEDOT) microelectrode arrays on indium tin oxide glass are reported. They can be used to manipulate the differentiation of human mesenchymal stem cells (hMSCs). In the devices, the rGO material functions as an adhesive coating to promote the adhesion and alignment of hMSC cells and to accelerate their osteogenic differentiation. The poly(L-lysine-graft-ethylene glycol) (PLL-g-PEG)-coated PEDOT electrodes serve as electroactive drug-releasing electrodes. In addition, the corresponding three-zone parallel devices operate as efficient drug-releasing components through spatial-temporal control of the release of the drug DEX from the PEDOT matrix. Such devices can be used for long-term cell culturing and controlled differentiation of hMSCs through electrical stimulation.

Protocols: The hMSCs (Neuromics, Edina, MN) used in experiments were at passage 3-9. Each passage of hMSCs was maintained on the TCPS dishes with a pre-coating of Geltrex reduced growth factor basement membrane matrix (Invitrogen, CIBCO, NY). All hMSCs were maintained in the growth medium, Dulbecco's modified Eagle's medium-low glucose (DMEM-LG) supplemented with mesenchymal cell growth supplement (MSCGM, Lonza) containing L-glutamine, penicillin, and streptomycin, and incubated in an atmosphere containing 5% CO2 at 37 °C. The medium was replenished every 3 to 4 days. For osteogenic differentiation, the hMSCs were cultured in the osteogenesis induction medium, DMEM-LG supplemented with mesenchymal stem cell osteogenesis kit (Chemicon, Cat. No. SCR028), and incubated on the TCPS dishes (control) and test devices. To study the drug release from the devices, hMSCs were cultured in the osteogenesis induction medium in the absence of DEX. The fresh medium was replaced every 2 to 3 days.

Figure: a–d) Osteocalcin expression in hMSCs cultured on rGO–PEDOT microelectrode arrays of various sizes (rGO–PEDOT-20, rGO–PEDOT-50, rGO–PEDOT-100), revealed through immunofluorescence staining. Cells were cultured for 9 days in osteogenesis induction medium in the absence of DEX; drug release was modulated electrically through three cycles of ES (three-day interval); osteocalcin (green) revealed the bone matrix and DAPI (blue) revealed the nucleus. e) Enlarged view of immunofluorescence of osteocalcin expression in hMSCs cultured on rGO–PEDOT-100. Arrows indicated the formation of bone matrix nodules. Scale bar: 100 μm. f) Schematic representation of some bioelectronic features integrated into our rGO–PEDOT devices. doi: 10.1002/adfm.201203631

Conclusion: Authors explored the effect of the dimensions of the rGO–PEDOT microelectrode arrays on the cell spreading and expression of differentiation; whereas the smaller rGO–PEDOT-20 array exhibited better cell alignment ability, the larger rGO–PEDOT-100 exhibited better performance at inducing osteocalcin expression in hMSCs. They also found that using three-zone parallel devices made it possible to release drugs at three points in time. This concept could presumably be extended to release different types of drugs at different lineages on defined patterns. Eventually, such devices might be applicable in tissue engineering and regenerative medicine.

I plan on frequent updates on ours and others development of Osteogenesis Assays for Drug Discovery.

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