Chemical gradients
A technology of concentrated and polymeric materials, applied in medical science, prosthetics, tissue regeneration, etc., can solve the problems of lack of providing non-instantaneous and/or physiologically relevant chemical gradients, and only suitable for injection of viral vectors
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Embodiment 1
[0078] Devices Containing a Single Microchannel
[0079] In one variation, an implantable device is fabricated that provides a chemical gradient and enables the localized delivery of specific growth factors within the microchannels through which axons will grow. For comparison purposes of this variation, Figure 1A Lumens or microchannels 11 within catheter 10 are shown. Microchannel 11 contains an active agent (not shown) to provide at least one transient region of the desired chemical potential. However, the active agent concentration over the length of the microchannel is difficult to utilize Figure 1A structure to control. As another comparative example of this variation, Figure 1B A microchannel 12 containing embedded microparticles 13 within a catheter 11 is shown. Microparticles 13 are impregnated with active agents (not shown), such as drugs or growth factors, and may be biodegradable. Microparticles 13 can predictably degrade or otherwise release the active a...
Embodiment 2
[0081] Devices containing multiple microchannels
[0082] In some embodiments, the devices described herein comprise a plurality of microchannels. Such a device can be used to stimulate axonal growth across the gap. When axons must grow across gaps, it is often desirable to segregate particular morphologies or types of axons into different compartments or spatial regions. Such separation can be used for the repair of sensory and motor branches and / or the development of closed-circuit peripheral neural interfaces. Furthermore, such separation can be achieved by arranging a plurality of fibers described herein around a plurality of microchannels of a device described herein, wherein the fibers vary in the amount and / or type of growth factor delivered to the different microchannels. and / or differ in the steepness of the chemical gradients provided in the different microchannels. In this way, specific types of axons from mixed neural populations can be induced to enter specific...
Embodiment 3
[0086] Methods of Forming Chemical Gradients
[0087] with Example 1 Figure 1C General Structure of the Device The device was used to form a chemical gradient according to one embodiment described herein as follows. First, poly(DL-lactic-co-glycolic acid) (PLGA) coiled fibers were fabricated. The biodegradable PLGA (85:15) copolymer (0.84 intrinsic viscosity (i.v.), 135,000 weight average molecular weight (MW)) was made into fibers using a wet spinning process. Briefly, 20 wt% PLGA solutions were completely dissolved in dichloromethane (Sigma-Aldrich, St. Louis, MO). This solution was filled with a glass syringe (gas-tight, Hamilton, Reno, NY) and injected into a 1.5-cm diameter tube filled with isopropanol to form fibers. Prewashed Mylar substrates were used as collection reels. Under many possible spinning parameters, the spinning solution injection rate and fiber collection speed were controlled at 1.8 mL / h and 8.5 m / min, respectively, to obtain 30 μm diameter fibers. ...
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Abstract
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