元心科技

The Iron Bioabsorbable Scaffold is a new type of therapeutic product used to treat diseases related to vascular occlusion, that can replace metal stents and polymer bioabsorbable scaffolds. Biotyx provides scaffold information in order to spread relevant knowledge to patients. The information does not replace the medical advice of the doctor, nor does it mean that the patient prefers or recommends treatment.

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Stent intervention is an effective treatment for vascular stenosis. At present, the stents used clinically are mainly permanent stents, which are mainly characterized by long-term dual antibody, late thrombosis, fatigue fracture of stents, and difficulty in secondary intervention. Besides, artifacts produced by metals can affect magnetic resonance (MRI) angiography and computed tomography (CT) angiography. The ideal stent should provide sufficient mechanical support to the lesion site and be gradually absorbed by the body after the vascular healing. Bioabsorbable scaffolds were developed based on this concept.

Bioabsorbable scaffolds are made of biodegradable/corrosive materials with the purpose of "disappearing after completion of the task". After implantation in the patient, they can initially support the diseased blood vessels and prevent the negative remodeling of the diseased blood vessels. With the improvement of the peripheral environment of the diseased vessels and the completion of the remodeling of the vascular structure, the scaffolds in the vessel gradually degrade/corrode and are absorbed. Compared with permanent stents, the advantages of absorbable scaffolds can be summarized as follows:

(1) short-term reduction of vascular elastic retraction and acute occlusion to prevention restenosis;

(2) long-term can reduce stent thrombosis and shorten the time of antiplatelet treatment;

(3) eliminate the artifacts of CT and MRI and other imaging examinations during the follow-up;

(4) can be used in the same place to intervene for many times.

Due to the many advantages of bioabsorbable scaffolds, many companies or research institutions are carrying out research in the world. Currently, bioabsorbable scaffold materials under development include polylactic acid, polycarbonate, magnesium alloy, ferroalloy and zinc alloy.

Polylactic acid scaffolds have good biocompatibility and degradability. There are many kinds of polylactic acid scaffolds that have been used in preclinical and clinical evaluation, and some of them have been certified and started to be sold. Absorb coronary scaffolds obtained the European CE certification and FDA approved and sold in Europe and the United States respectively in October 2010 and July 2016. Delisting was announced in September 2017, mainly due to the 3-year study show that the Absorb was significantly inferior to the mainstream permanent stent at the associated instrumentation composite endpoint, target vessel myocardial infarction, and late/extreme late stent thrombosis. Lepu's NeoVas scaffold was approved by CFDA as a medical device registration certificate in February 2019.The substrate materials of both the Absorb and NeoVas scaffolds are PLLA. Due to the limitation of the intrinsic properties of the materials, the thickness of the scaffolds is about 150μm, and its performance is inferior to that of the permanent scaffolds. Besides, its product specifications are also small, which can only cover very small patients’ proportion.

Magnesium stents have been widely studied for their good biocompatibility and better mechanical properties than polymer stents. Currently, Biotronik's Magmaris scaffolds have been certified and have been available in the EU and Hong Kong in 2016 and 2018 respectively. The mechanical properties of magnesium scaffolds are still lower than those of permanent scaffolds, but slightly better than those of PLA scaffolds. The strut thickness of the scaffolds is 150μm, and the product specifications are less. Generally speaking, the performance of magnesium scaffolds is similar to that of PLA scaffolds. The corrosion rate of magnesium is too fast to maintain an effective support vessel for 3 to 6 months after implantation.

Zinc and its alloys have also been developed for bioabsorbable vascular scaffolds. Although some studies have reported that zinc and its alloys have good biocompatibility and a possible appropriate corrosion rate, the mechanical support properties of zinc scaffolds need to be further improved.

Pure iron has good biocompatibility, and it is easy to obtain excellent mechanical properties after proper modification. Biotyx Medical (shenzhen) co., LTD. has developed the IBS series scaffolds which is the only iron based absorbable scaffolds in the world. Through structural design and coating regulation, the problem of slow iron degradation was overcome. Due to high material strength and low amount of scaffold material, the MRI compatibility was similar to that of stainless steel scaffold. At the same time, through material and technological innovation, the iron-based scaffold has the same mechanical properties, specifications and operation ability as Xience Prime. It can solve the problems of other absorbable scaffolds with poor mechanical properties, large size, and small specifications, which cannot be effectively applied to complex lesions (such as calcified lesions, chronic complete occlusion lesions, branch lesions, and extremely tortuous lesions) and diseased vessels with diameters less than 2.5mm. It is the only promising alternative to permanent metal scaffolds technology.
Iron - based scaffolds have good mechanical support performance. On the premise of achieving the same support effect, the thickness of iron scaffolds is far less than that of magnesium alloy scaffolds and PLA scaffolds. At present, the thickness of IBS series products is about 70μm, which is the smallest scaffolds in the world. In view of the long degradation cycle of iron and the slow elimination of solid degradation products, Biotyx Medical (shenzhen) Co., Ltd. has developed an innovative Zinc-PLA composite coating technology to slow down the early degradation of iron, ensure the effective support of iron scaffolds in the early stage, and avoid the early fracture of scaffolds. In the later stage, the acidic environment created by the degradation of the polymer coating accelerates the degradation, removes the mechanical constraint of the scaffold on the blood vessels, and the degradation products can be effectively absorbed, so as to achieve the degradation of the iron-based scaffold in vivo.

Compared with permanent stent:

1. Iron-based absorbable scaffolds avoid the short-term and long-term risks associated with the permanent retention of implants, such as long-term inflammation, displacement and restenosis caused by long-term stimulation of foreign bodies;

2. Avoid the risk of stimulation to blood vessels or even perforation caused by long-term fatigue fracture (29% permanent stent fracture rate at autopsy);

3. Permanent stents impact MRI, CT and other medical imaging, but the problem will be solved after the degradation of iron-based scaffolds;

4. After the degradation of the iron-based absorbable scaffolds, the blood vessels will no longer be bound, and the patients will not suffer the trauma, pain and economic loss caused by the secondary intervention and re-expansion after the implantation of the permanent metal stent or the surgical removal of the stent.

At the same time, the iron-based absorbable scaffolds overcome the shortcomings of PLA and magnesium scaffolds. Due to the limitation of mechanical properties of materials, PLA scaffolds have high strut thickness and few product specifications, which can only be applied to simple lesions. Magnesium scaffolds also have the problem of large wall thickness and fast degradation rate in the early stage, which cannot guarantee the effective propping up of blood vessels in the early stage. In contrast, the iron scaffolds can significantly reduce the strut thickness and material consumption on the basis of guaranteeing the mechanical support in the early stage. Besides, it has excellent operating performance and a wide range of product specifications, which greatly improve the applicable range of patients.

In general, the advantages of iron-based absorbable scaffolds are obvious. It has the advantages of biodegradable absorption that the permanent stents do not have. Meanwhile, their mechanical properties are similar to those of permanent stents. The successful development of the iron-based absorbable scaffolds project of Biotyx Medical (shenzhen) co., LTD. will change the situation that China has been copying or making small innovations in foreign technologies in the stage of BMS and DES in the vascular stent field, achieve the overtaking of biodegradable scaffold (BRS) and lay a scientific and technological foundation for China's biomedical materials industry to become an international leader. The success of iron scaffolds will have great social significance in alleviating the suffering and prolonging the life of patients.

Biotyx Medical (Shenzhen) Co., Ltd.

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http://www.lifetechmed.com/

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