Early Membrane Responses to Magnetic Particles are Predictors of Particle Uptake in Neural Stem Cells

Abstract

Magnetic particles (MPs) offer several advantages for neural cell therapy, but limited particle uptake by neural cells is a barrier to translation. It is recently proved that tailoring particle physicochemical properties (by enhancing their iron content) dramatically improves uptake in neural stem cells (NSCs)—a major transplant population. High‐throughput screening of particles with varying physicochemical properties can therefore aid in identifying particles with optimal uptake features, but research is hampered by the lack of simple methodologies for studying neural cell membrane responses to nanoparticle platforms. A high‐resolution–high throughput method has been used to study early membrane responses of primary rodent NSCs to particles of variant magnetite loading, to attempt to correlate these responses with known particle internalization profiles. Membrane imaging is enhanced through sequential staining with osmium (O) and thiocarbohydrazide (T), a method termed OTOTO, combined with field‐emission scanning electron microscopy (FESEM). A five‐point classification system was used to systematically evaluate early MP‐induced membrane responses to particles possessing distinct physicochemical properties. Significantly different profiles of membrane activation were noted that correlate with particle uptake profiles. It is suggested that our method can serve as a valuable predictor of particle internalization in neural cells for diverse particle platforms.

Nanoengineering neural stem cells on biomimetic substrates using magnetofection technology

“…To quantify any potential differences, the extent of membrane activity of NSCs grown on the two substrates was assessed using a previously developed 5-point classification system for membrane features. 9 In this assessment, four out of the five markers of membrane activity (extent of membrane ruffling and numbers of pits, filopodia and nanopodia) were significantly elevated in NSCs grown on glass when compared to the NSCs grown on collagen (Figure 5B-E). A tendency towards increased numbers of circular ruffles on the membranes of glass cultured NSCs was also noted but was not found to be significantly different ( Figure 5F).…”

“…9 Here, fixation and repeat staining of cells using osmium and thiocarbohydrazide can allow for detailed analysis of cellular membranes and polymeric materials with scanning electron microscopy.…”

“…9 Briefly, one field in the centre of each cell was analysed at X20000 magnification (corresponding to 25 µm …”

“…9 The feasibility of applying this methodology to study NSC membrane activity in soft matrices has never been established.…”

Endocytotic Potential Governs Magnetic Particle Loading in Dividing Neural Cells: Studying Modes of Particle Inheritance

“…Furthermore, it is well established that uptake of nanoparticles is mediated via a range of endocytotic mechanisms [9][10][11][12]. In this context, it should be noted that NSCs have relatively small cell bodies, elaborate limited amounts of cell membrane and appear in ultrastructural observations to possess comparatively quiescent membranes [13]. How neural transplant cell populations with greater levels of endocytotic activity handle such high magnetite content MPs is unclear, but it can be postulated that such cell/MP combinations can result in greater enhancement of cell labeling for neural transplant applications.…”