A Self-Assembling Injectable Biomimetic Microenvironment Encourages Retinal Ganglion Cell Axon Extension in Vitro

Abstract

Sensory-somatic nervous system neurons, such as retinal ganglion cells (RGCs), are typically thought to be incapable of regenerating. However, it is now known that these cells may be stimulated to regenerate by providing them with a growth permissive environment. We have engineered an injectable microenvironment designed to provide growth-stimulating cues for RGC culture. Upon gelation, this injectable material not only self-assembles into laminar sheets, similar to retinal organization, but also possesses a storage modulus comparable to that of retinal tissue. Primary rat RGCs were grown, stained, and imaged in this three-dimensional scaffold. We were able to show that RGCs grown in this retina-like structure exhibited characteristic long, prominent axons. In addition, RGCs showed a consistent increase in average axon length and neurite-bearing ratio over the 7 day culture period, indicating this scaffold is capable of supporting substantial RGC axon extension.

A sulfonated reversible thermal gel for the spatiotemporal control of VEGF delivery to promote therapeutic angiogenesis

“…SPSHU‐PNIPAM was recovered by precipitation in diethyl ether, rotoevaporation, purified via dialysis (MWCO 12–14 kDa), and lyophilized, yielding a light‐yellow product. Polymer characterization was performed as described previously to confirm material produced …”

“…[26][27][28] A sulfonated reversible thermal gel composed of poly(serinol hexamethylene urea) (PSHU) conjugated with PNIPAM and sulfonate groups (SPSHU-PNIPAM) has been developed for the delivery of angiogenic growth factors. 29 The PSHU backbone is highly functionalizable and has been shown to exhibit a favorable microenvironment for neuronal [30][31][32] and cardiac 33 tissue engineering applications. Localized and sustained release of angiogenic factors was achieved by conjugating PNIPAM and sulfonate groups to the PSHU backbone, allowing for physical encapsulation and electrostatic binding affinity with angiogenic factors, respectively.…”

Injectable Carbon Nanotube-Functionalized Reverse Thermal Gel Promotes Cardiomyocytes Survival and Maturation

“…Samples were prepared as previously reported. 20, 26, 36, 38, 41 Briefly, the polymers in solution (1% w/w) were allowed to form a gel at 37 °C. Warm water was then put on top, and the samples were frozen immediately by liquid nitrogen immersion.…”

“…20 The RTG-lysine system provides a straightforward delivery vehicle for CMs, as it transitions to a three-dimensional (3D) gel-based matrix seconds after reaching body temperature, enabling 3D CMs growth. 20 In addition, the PSHU backbone of the RTG-lysine contains several free amine groups for further functionalization, 26, 36–39 allowing our system to be amenable for a wide variety of bioconjugations, providing versatility and adaptability for different applications. 20, 26, 36, 40 Moreover, PSHU is also highly biomimetic and biocompatible, since amide ester bonds in the backbone structure provide characteristics similar to those found in natural polymers, such as collagen and gelatin.…”

Reverse Thermal Gel for In Utero Coverage of Spina Bifida Defects: An Innovative Bioengineering Alternative to Open Fetal Repair

“…Cells and various therapeutic agents (drugs, growth factors) can be mixed within the room temperature (RT) solution and become encapsulated when the gel forms, providing a scaffold for cells or a vehicle for controlled therapeutic agent release. RTGs have been used as cellular scaffold devices and drug/biomolecule delivery vehicles for both in vitro and in vivo applications for cardiac tissue engineering, retinal ganglion cell cultures, and spinal cord injury . For an application in fetal repair of NTDs, RTGs provide a novel, minimally invasive method for coverage of the NTD at an earlier gestational age.…”