A Novel Methodology for Bio-electrospraying Mesenchymal Stem Cells that Maintains Differentiation, Immunomodulatory and Pro-reparative Functions

Mesenchymal stem cells (MSCs) are an important cell source for tissue engineering (TE) and cell therapies for several reasons including ease of isolation from multiple tissues, uncomplicated ex vivo culture, ability to self-renew and differentiate into numerous cell types, MSC/immune cell interactions and pro-reparative properties. Current MSC therapies involve administration via intravenous (I.V.) injection. However, this can result in MSC entrapment and failure to target injured site. In TE, artificial 3D constructs are being investigated as strategies for direct delivery of MSCs to a target area. However, these constructs have numerous limitations including lack of cell infiltration, poor cell functionality and limited diffusion of nutrients and oxygen through the scaffolds. We are investigating the jetting methodology bio-electrospraying (BES) as an alternative strategy for MSCs delivery in vivo that may overcome obstacles associated with I.V. injections and scaffold transplantation. For BES in vivo, low voltages, stable jetting and a single needle configuration are highly desirable. A commercially available electrospray apparatus Spraybase (R) was used to electrospray mouse bone marro-wderived MSCs (mBMSCs) at low voltages (similar to 3-6 kV) in vitro. Stable jetting conditions with a single needle at these low voltages were established by employing a ring-shape electrode for potential difference, specific culture medium and the use of high mBMSCs numbers to overcome viscosity difficulties. The viability and functionality of the mBMSCs following BES was determined by analysing expression of specific surface markers, multilineage differentiation, suppression of T-cell activation and proreparative capabilities. We show that mBMSCs post-BES functioned similarly to non-bio-electrospray (non-BES) control mBMSCs for all parameters examined. This methodology may subsequently enable targeted delivery of MSCs to an injury site in vivo and potentially avoid the complications associated with MSCs entrapment and the limitations associated with artificial scaffolds.