Spontaneous association of glial cells with regrowing neurites in mixed cultures of dissociated spiral ganglia

Abstract

Evidence from developmental and regeneration studies of the cochlea and other tissues give reason to hypothesize a role for non-neural cells in the growth and regeneration of cochlear spiral ganglion nerve fibers. We examined the spontaneous associations of regrowing neurites and non-neural cells in mixed cultures of dissociated newborn mouse spiral ganglia. After 7 days in vitro, non-neural cells formed a confluent layer in the culture well. Regrowing neurites grew atop this layer, forming non-uniform patterns that were similar to those formed by endogenously expressed laminin-1, entactin and integrin β4, but not fibronectin or tenascin. In cultures grown for 42 hours and maintained in three different growth media, all regrowing neurites were preferentially associated with spindle-shaped non-neural cells. The spindle shaped cells incorporated BrdU in culture and were immunoreactive for the proteins S100, laminin-1, laminin-2, Sox10, P75 and connexin29 but negative for fibronectin and GFAP. These cells existed in the culture within a much larger, general population of fibronectin positive cells. Immunolabeling of fixed cochleas from neonatal mice localized Sox10, P75 and connexin29, to peripheral nerve bundles. The observed expressions of protein markers and the bipolar, spindle shape of the neurite-associated cells indicates that they are derived in vitro from the original Schwann or satellite cells in the ganglion or spiral lamina. The spontaneous and preferential association of neurites in culture with mitotic Schwann cells highlights the potential contribution neurite-Schwann cell interactions may have in promoting the growth and regrowth of damaged spiral ganglion neurons in the cochlea.

Photopolymerized microfeatures for directed spiral ganglion neurite and Schwann cell growth

“…Along with SGN neurite contact guidance, it may also be advantageous to develop an understanding of SGSC response to cell relevant physical features due to their close association with SGNs and their processes[33,56,57]. For example, SGSCs closely associate with regenerative neurites in vitro and express neurotrophins such as BDNF and NT-3 that provide crucial trophic support to maintain SGN viability and support neurite growth[35,56,57].…”

“…For example, SGSCs closely associate with regenerative neurites in vitro and express neurotrophins such as BDNF and NT-3 that provide crucial trophic support to maintain SGN viability and support neurite growth[35,56,57]. Accordingly, the extent of SGSC alignment in response to patterns with constant periodicity but varied feature amplitude was evaluated by co-culturing SGSCs with SGNs on micropatterned HMA-co-HDDMA polymers with 1, 3, and 8 μm channel amplitudes and 50 μm periodicity (Fig 7E,F).…”

Dual embryonic origin of the mammalian otic vesicle forming the inner ear

“…6C). P75 is a neurotrophin receptor that is often used as a NCC marker and is also expressed in CVG neurons (Whitlon et al, 2010;Whitlon et al, 2009). P75 appears to colocalize with reporter cells in the CVG of Wnt1-Cre;RCE GFP/+ mice (Fig.…”

Structure and development of cochlear afferent innervation in mammals

“…Recent data suggest that SG Schwann cells (SGSCs) support and direct SGN neurite outgrowth and probably facilitate fasciculation (73,183). In addition, SGSCs were found to produce BDNF and NT-3 that may mediate paracrine neuronglial interactions in the auditory nerve (59).…”