Table 3 Selection of investigations carried out into potential protective mechanisms for cell cargos
Aim of study | Cell type | Needle size | Flow rate | Brief description of results | Refs. |
|---|---|---|---|---|---|
Use of hydrogels | |||||
Improving viability during injection by alginate hydrogels | Human umbilical vein endothelial cells and adipose stem cells, rat MSCs, and mouse neural progenitor cells | 28 G needle on 1 mL syringes | 1000 µL/min | Crosslinked alginate hydrogel produced highest viability. Increasing or decreasing G′ reduced protective effect. Cells in non-crosslinked alginate exhibited lower viabilities than media. Data suggested extensional flow at needle entrance was chief cause of cell death | |
β-hairpin peptide hydrogel as carrier during syringe flow | MG63 | 26 G needle on 1 mL syringe | 4, 6 and 8 mL/h | Only gel at the capillary wall experienced a velocity gradient, whereas the rest was subject to minimal shear rate. Hydrogels had no apparent effect on viability of encapsulated cells | |
Injectable fibrin matrix to enhance vascularisation | Bone marrow mononuclear cells (BMMNCs) | 100 µL injection—Needle size not mentioned | Not mentioned | Device was constructed for simultaneous injection of fibrinogen and thrombin solutions. Implantation of BMMNCs in fibrin resulted in better tissue regeneration and neovascularisation | |
Growth factor supplemented matrigel for cell delivery | C2C12 myoblasts | Not mentioned | Slow-exact rate not mentioned | Results showed that the combination of matrigel as a cell carrier for myoblasts with growth factors is recommended for the generation of muscle in vivo | |
Use of microparticles | |||||
PLGA particles for intracerebral delivery | Neural stem cells | 22 G needle on a 50 µL gastight Luer-tip syringe | 2 μL/min | Plasma polymerised allylamine-treated MPs were used. Cell attachment was influenced by curvature, material, electrostatic charge and surface motif of particles, and the number of cells in the culture | |
Nerve growth factor (NGF)-releasing PLGA microparticles | Foetal rat (E16-E17) brain cells | 22s-G needle on a 10 µL syringe | <1 µL/min | Dose of NGF delivered can be modified by changing quantity of microparticles or NGF release rate. Activity of neo-tissues with NGF-enriched microenvironments increased in in vivo and in vitro | |
Automated vs. manual systems | |||||
Compare manual and automated injection | Neural progenitor cells and bone marrow stromal cells | Automated device for μL syringes (MEDRAD Inc.) | — | Automated delivery resulted in less variability in amount delivered. No significant difference in viability attributable to method of injection | |
