Basic Questions and Answers of Iron Bioabsorbable Scaffold
Question & Answer
Q:What kind of situation is a vascular scaffold required? 
A:The scaffold is used to open and support the blood vessel when the vascular stenosis leads to ischemia of related tissues. The advantage is that this scaffold surgery is a minimally invasive surgery. Under local anesthesia, a needle is inserted into the blood vessel at the wrist or thigh root of the patient, and then the wireguided catheter implants the scaffold. If it is a wrist approach, the patient can walk down after one or two hours of surgery. 

Q:Is the scaffolld ackward technology? 
A:When the blood vessel stenosis causes disease, the scaffold is the first choice in the world. Only when the scaffold is not suitable, bypass or other surgical operations are considered. Cardiac bypass is a technology that was available 20 years ago. As for which operation is more suitable, the doctor will fully evaluate. 

Q:Why do you want a bioabsorbable scaffold?
A:The scaffold aims to open the narrow or blocked blood vessel and end the patient's illness, but the scaffold will bring other problems after implantation. One is that to ensure  the scaffold has always been working, the patient should take long-term anticoagulant. Another is that since the scaffold implanted, about 2% of patients have restenosis at the scaffold site (coronary scaffolds, commonly known as heart scaffolds); the rate of restenosis of blood vessels below the knee is higher, and the treatment of restenosis within the scaffold is more difficult. The other is that children’s blood vessels grow as the child grows up. The scaffold will hinder the growth of blood vessels. Besides, the scaffold as a foreign body will affect the image quality during later medical examinations such as MRI and CT. 

Q:What are the bioabsorbable scaffolds? Which is the best? 
A:The scaffold materials currently under study are plastic scaffolds, magnesium alloy scaffolds, zinc alloy scaffolds and iron alloy scaffolds. The polymer scaffold was the first to be studied. The representative polymer scaffold is the ABSORB scaffold from Abbott, which received CE certification in 2011 and the US FDA registration in 2016, but was delisted in 2017 because the incidence of adverse events was higher than that of permanent scaffolds. The reason is that the strength of the polymer material (a plastic) is not as good as that of the metal scaffold, and the scaffold must be made hypertrophy, which causes clinical problems. Among the metal (magnesium, zinc, iron) scaffolds, only magnesium scaffolds and iron scaffolds have entered clinical trials. Only Magmaris, a magnesium alloy scaffold from  Biotronik Company in Germany, entered the clinical trial in the world and obtained CE certification in 2017. It is currently in the post-market clinical stage. For the iron scaffold, only Biotyx's IBS scaffold started clinical trials in March 2018. Zinc scaffolds have not entered clinical trials. Among all the scaffold materials, only the mechanical properties of iron scaffold materials are equal to the latest generation of permanent scaffold materials, zinc alloy and magnesium alloy are lower than half of the permanent scaffold, and plastic is only one-tenth of the permanent scaffold. As for which scaffold is best, clinical results are needed to confirm. 

Q:Which patients benefit most from implanting a bioabsorbable scaffold? 
A:Of course, all bioabsorbable scaffolds for vascular stenosis are theoretically superior to permanent scaffolds in the long term. The most profitable ones are young patients and patients who cannot take anticoagulants for a long time due to various reasons. Of course, there are currently no pulmonary scaffolds and sub-knee scaffolds for infants in the world. Bioabsorbable scaffolds bring new treatment methods to these patients, and naturally they are very profitable. 

Q:Why is only Biotyx developing iron scaffold in the world?
A:The biggest challenge of iron-based materials used in vascular scaffolds is that iron degrades slowly in the human environment, and degradation products are slowly absorbed. Biotyx has found a technical path to solve this problem. It is wrapped with polylactic acid outside the iron support, and the polylactic acid coating is used to degrade to create an acidic microenvironment because iron can be quickly degraded into soluble ions in an acidic environment. We then infiltrate nitrogen into the iron to increase the mechanical properties of the iron exponentially, so that sufficient support can be achieved with very little iron. For example, the amount of iron in a conventional iron scaffold is only equivalent to a person's iron intake in less than a week. We began to develop iron scaffolds in 2006. During the past 10 years, we have been constantly discovering and solving problems. We have applied for international patent protection for these technologies. 

Q:How does iron scaffold degrade and absorb in human body? 
A:Our research found that iron is degraded into iron ions in an acidic microenvironment, part of which is directly bound by the blood and enters the body's iron circulation, and part of it is deposited in the form of microparticles on the walls of blood vessels in tissues. These particles will be cleaned by macrophages and converted into hemosiderin in the body, that will enter the body's sewer lymphatic system, and be subsumed in the body's iron circulation. If there is internal bleeding in our body, the iron left after the blood is absorbed will also return to the iron circulation in this way. The iron content of a conventional scaffold is only equivalent to the iron in 20ml of blood, and 20ml is equivalent to the volume of the thumb.

Q:Is iron scaffold biotoxic?
A:The iron scaffold contains only iron (94%), zinc (6%) and nitrogen (<0.1%). Iron and zinc are essential elements in the human body. In addition to 21% oxygen in the air, the remaining 79% is nitrogen. Trace amounts of polylactic acid will degrade into carbon dioxide and water. There are no other heavy metals or toxic elements, so it has good biocompatibility. There are 4-5 grams of total iron in our body. The blood transports 20mg of iron every day, and the iron  ingested into the blood every day is 1-2mg. The iron content of a conventional iron scaffold is less than 10mg. The human body ingests 10-20 mg of zinc per day, while a conventional iron scaffold has less than 1 mg of zinc, and a scaffold only corresponds to a few hours of zinc intake. Animal experiments and human experiments have proved that iron scaffolds have good biological safety.

Q:What is the MR (magnetic resonance) compatibility of the iron scaffold? 
A:Iron is a magnetic material, which seems to be incompatible with MR in theory. However, our laboratory and animal experiment tests show that its MR compatibility is equivalent to the current permanent scaffold. Our label indicates that it is "MR condition safe", that means under certain conditions, MR is safe, and this safe boundary condition is  exactly the same as permanent scaffold. This is because our iron consumption is very small, even less than that in the stainless steel scaffold. When the scaffold degrades, it becomes "MR safe." 

Q:How long can the iron scaffold degrade in the human body? 
A:Our preliminary clinical results found that in the human coronary artery, it degrades about 60% in six months and about 80% in one year. This can be roughly estimated that it can be completely degraded in about 1.5-2 years. More clinical data in the future will provide more accurate and comprehensive data of degradation. 

Q:Can I go through the security gate with an iron scaffold implanted? Will the security inspection machine send out a warning? 
A:According to our testing result, you can be passed, and the security inspection machine will not find out. The reason is still because the scaffold is very small, and the iron amount is lower than the detection limit of the machine. 

Q:How long does the double-antibody medicine should be taken after the iron scaffold is implanted? 
A:The time of endothelialization of iron scaffolds (tissue completely wraps the scaffold, separates from the blood, and no longer can cause thrombosis) is shorter than permanent scaffolds, so currently the double-antibody time of iron scaffolds is the same as that of permanent scaffolds, which is one year. In the future, more clinical data will provide more references. The double-antibody time of the polylactic acid absorbable scaffold is generally more than 3 years. 

Q:Are there any special requirements for iron scaffold surgery? 
A:It is  basically the same as permanent scaffolds, and there is no need to emphasize the PSP operation of the polylactic acid scaffold and the 4P operation of the magnesium alloy scaffold. The main points of PSP / 4P operation are pre-expanding the narrowed blood vessel with a balloon before scaffold placement, accurately measuring the diameter of the blood vessel with an OCT (intravascular optical coherence imaging) catheter, and expanding the scaffold with a high-pressure balloon after scaffold implantation. These additional operations will bring additional costs. 

Q:Is it available to implant iron scaffolds  now? 
A:At present, the product has not been approved by the government, and no iron bracket can be sold. The current clinical trials in China are: 1. Coronary scaffold IBS® hosted by Academician Gao Runlin of Fuwai Hospital; 2. Under-knee scaffold IBS® TitanTM chaired by Professor Guo Wei of PLA General Hospital (301 Hospital); 3.Children's pulmonary artery scaffold IBS® AngelTM hosted by Professor Zhiwei Zhang. Since the first implantation of our iron scaffold in March 2018, more than 100 cases have been implanted in various clinical trials around the world, which has initially proved the safety and effectiveness of iron scaffolds. Patients who are willing can contact the doctor of the relevant clinical trial. After evaluated by doctor, the eligible ones can be added to our clinical trial. 

Q:When is the iron scaffold expected to be approved? 
A:This is difficult to estimate. Vascular scaffold is the highest-risk medical device, so clinical trials and government approvals are long-term works and  uncontrollable. The child ’s scaffold must have been approved first, then the sub-knee scaffold, and then the coronary scaffold. We have submitted the CE certification application for children's scaffolds and it is under the review process. Please pay attention to the information on our website for the specific process. 

Compile Author:szhotdog