Nasolacrimal stent with shape memory as an advanced alternative to silicone products

et al. 2021

Small

Self Cite

Shape memory materials have been successfully applied to minimally invasive implantation of medical devices. However, organ‐movement‐specific shape programing at a microscale level has never been demonstrated despite significant unmet needs. As vein‐to‐artery grafting induces vein dilation and stenosis, a polymeric self‐enclosable external support (SES) is designed to wrap the vascular out‐wall. Its micropores are programmed to increase sizes and interconnections upon dilation. Vessel dilation promotes venous maturation, but overdilation induces stenosis by disturbed blood flow. Therefore, the unique elastic shape‐fixity of SES provides a foundation to enable a stable microscale shape transition by maintaining the vein dilation. The shape transition of micropore architecture upon dilation induces beneficial inflammation, thereby regenerating vasa vasorum and directing smooth muscle cell migration toward adventitia with the consequent muscle reinforcement of veins. This game‐changer approach prevents the stenosis of vein‐to‐artery grafting by rescuing ischemic disorders and promoting arterial properties of veins.

Section: Methodsmentioning

confidence: 99%

Dilation‐Responsive Microshape Programing Prevents Vascular Graft Stenosis

Yi¹,

Shin

et al. 2021

Small

Self Cite

“…10,11 We previously reported that our shape memory polymer (SMP) reduced biofilm formation by 75% compared to silicone. 12 Since then, further progress has been made to enable user-specified control of the tube diameter in the treatment of glaucoma patients. The goal of the present study is to demonstrate that a SMP tube can be programmed to enable self-expansion when inserted into the silicone tube and thereby to control small and large IOP drops before and after expansion, respectively.…”

Section: ■ Introductionmentioning

confidence: 91%

“…13,14 The shape recovery temperature (T m ) of our SMP can be controlled from 32 to 44 °C by adjusting the degree of cross-linking as reported previously. 12,15 In this study, the T m of SMP was set to 37 °C in order to prevent unexpected shape recovery in contact with the body fluid during the deployment process. The temperature of the warm saline was 39−40 °C, and the eye was exposed to this warm saline for 1 min so that the conjunctiva of the eye was warmed up to reach the T m of the SMP tube.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Future studies will include (i) long-term validation of efficacy and safety, (ii) testing in a disease animal model, (iii) large animal experiments rather than the rabbit model, (iv) programming of a twostep self-diameter expansion from a temporary shape to a small degree of expansion and next to a large degree of expansion to enable more fine control of IOP, and (v) reverse shape programming from an original shape back to a temporary shape in case the IOP drop is controlled in the opposite way in alignment with the concepts of multishape memory and reversible shape memory in a recent review paper. 31 Because our SMP reduced the biofilm formation significantly (∼ 5 times) compared to silicone as shown in our previous study, 12 the current design demonstrates promising potential to control the IOP in a more predictable way by responding to the need to change pressure drops progressively.…”

Section: Acs Biomaterials Science and Engineeringmentioning

confidence: 99%

“…Amid an increasing number of cases of tube device implantation as opposed to trabeculectomy operation, − the Ahmed valve (New World Medical, Rancho Cucamonga, CA, USA) became a top choice around the world. ,, However, implantation of this device often results in too much drop of IOP (“hypotonic”) in the early phase because the fixed diameter of the drain tube does not allow for flexible control of the IOP drop. Moreover, because silicone is prone to chronic biofilm formation, outlet obstruction of silicone tubes limits successful treatment in the long term phase. , We previously reported that our shape memory polymer (SMP) reduced biofilm formation by 75% compared to silicone . Since then, further progress has been made to enable user-specified control of the tube diameter in the treatment of glaucoma patients.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shape Memory Tube Plug for Fine-control of Intraocular Pressure by Glaucoma Devices

Oh¹,

ACS Biomater. Sci. Eng.

Choi

et al. 2020

Self Cite

As a standard approach to treating glaucoma, a silicone tube device is inserted into the eye to drain water and thereby lower the intraocular pressure (IOP). However, the fixed diameter of the tube often results in too much initial water drain. Suture-sheaving of the outer tube wall also leads to random IOP drops over time. In this study, self-expansion of the inner tube diameter was achieved by inserting a shape memory tube into the silicone tube. The difference in controlling small to large IOP drops before and after tube diameter expansion was demonstrated via computational modeling, a flow pumping system, and rabbit experiments.

Laser‐Responsive Shape Memory Device to Program the Stepwise Control of Intraocular Pressure in Glaucoma

Choi

Kim

et al. 2023

Adv Funct Materials

Self Cite

There is an unmet need in the glaucoma clinic to control changes in the intraocular pressure (IOP), i.e., patient‐specific hypotony and tissue fibrosis‐mediated ocular hypertension, owing to the fixed tube diameter of the glaucoma drainage device. As a potential solution, the tube diameter can be adjusted, depending on the IOP, by shape memory polymer (SMP) and clinical laser systems, which can control the energy level, focus, and frequency by minimizing untargeted influences. To develop a translatable device, a laser‐responsive SMP with two additional elements: i) a tube with an intimal gel coating to release 5‐fluorouracil as an anti‐fibrotic drug and ii) a safety lock ring to block late hypotony in special cases is employed. When the SMP tube is inserted into a silicone tube and wrapped externally by the ring, intimal gel degradation and argon laser‐triggered diameter increase enable a three‐step IOP control. Sustained drug release of the intimal gel suppresses tissue fibrosis, and the ring prevents late hypotony by externally squeezing the silicone tube. The advanced design and functions are validated using computational in vitro and rabbit glaucoma models by determining clinic‐friendly argon laser parameters.