Titanium endoprostheses: made in Russia
Nano on bonesAlexey Torgashev, Correspondent of the Science Department of the Russian Reporter magazine
The mundane task is to make an implantable prosthesis. However, scientists from the N. F. Gamalei State Research Institute of Epidemiology and Microbiology are inventing a fundamentally new implant. It uses both titanium, specially manufactured at an aviation plant, and growth factors of stem cells prepared using the latest developments in molecular biology, genetic engineering and nanostructured assembly on surfaces.
Twisted joints, bone fragments sticking out of torn muscles, a blow to the spine – and immobility, often blood, sometimes disability and always pain. All these are characteristic signs of a bone fracture – the foundations of the human body. It is good if the fracture treatment is limited to plaster for a month or two. It's worse if you need a prosthetic implant. It's really bad if this prosthesis, usually titanium, is rejected and doctors, shaking their smart heads, say: "You, my dear, need a second operation." It is at least very painful.
Figuring out how to heal the bone quickly and as painlessly as possible is the task of modern technologies.
It's not the size that mattersHe has a smooth skull, a strong neck, solid dimensions, very serious eyes and a good smile.
Vladimir Lunin is the head of the project, the winner without five minutes and so on. He's sitting across from me, across the table, and I'm about to ask him an uncomfortable question, so I'm extremely hesitant.:
– Your laboratory is called... uh-uh… In general, there is the word "nano"…
–Biologically active nanostructures," he suggests.
– Well, yes… So, now it somehow sounds indecent. It is believed that nanotechnologists are... such... rogues from science. How do you like it yourself?
Why did I ask this question? Nanotechnology has recently been understood as any research on everything that is small. Biotechnologists suddenly became nanobiotechnologists, materials scientists – nanomaterialists, even nanocosmetics appeared, and some authors are talking about nanosapiences. And then there was the state corporation "Rusnano" with a budget of 130 billion rubles, which are not spent, but have been on the accounts for more than a year in order to save for approved projects. In a year, by the way, this corporation has approved only two projects, which personally gives me reason to doubt the advertised effectiveness and the future flourishing of the Russian nanoindustry, whatever that word means. I – and not I alone – suspect that the word "nano" is thrown into the Russian economic reality specifically so that it is unclear where the money will disappear. That is why I distrust any organization that uses the prefix "nano". No, really!..
On the other hand, I like Lunin, so it turns out that the question is inconvenient.
But he's good, he takes the question seriously and answers it just as seriously:
– You see, the selection criteria are important. On the one hand, any protein is 10 nanometers, and a viral particle is, say, 40. But size is not the only criterion. A nanoproduct is a product that is self–assembled. You will say: what is difficult here? Any living organism is a nanostructure: at the lower level, organelles are created from molecules, cells from organelles, and a person is assembled from cells. But it is important for a nanotechnologist to be able to control these processes.
ComponentsTitanium plates the size of a fingernail are packaged in plastic bags.
Before starting the experiment, they need to be sterilized – first by ultrasound, and then by high temperature in an autoclave. Then the plate is covered with a composite material – this is what Alexander Semikhin, a junior researcher and graduate student of Lunin's laboratory, is currently doing.
– We are preparing plates – an experimental prototype of a prosthesis used in fractures. To see how fast they are overgrown with cells," he says, squeezing out a suspension from a syringe that resembles toothpaste in color and density.
Sasha smears a thin layer of gruel on titanium and leaves the plate to dry. When the solution dries, the plate will be placed in a Petri dish with stem cells, which will have to attach to the surface, multiply and become bone tissue. Moreover, they should do all this faster than on a conventional titanium plate, not covered with a composite.
However, the word "ordinary" is also not quite correct here, since one of the "chips" of the project is nanostructured titanium. It is made by the Ufa State Aviation University using Damascus steel technology, which, as is known, has been forged for a long time. True, they do not forge here, but drag and roll, but the essence is the same: after broaching, the metal grains decrease to 100-300 nanometers, and its strength increases by two and a half times. Then the surface is treated so that it becomes rough.
– This is just polishing, – says Semikhin, displaying an electronic photo of the surface of titanium on the monitor, – and these pictures are different treatments: acid, sand. You see, the relief is different everywhere. We experimentally selected three variants on which cells grow better… Well, what else can I show you?..
Getting into a laboratory that works with knowledge from a dozen fields of science falls heavily on an unprepared soul. After a while, you begin to feel like a cockroach inside a tube receiver – there are many intricate designs, the purpose of which and the connection with the general plan are hidden from the mind as well as the general plan itself.
– Why is your project needed? I asked Vladimir Lunin.
– Our society is aging and more often "breaks down". On the other hand, young people began to suffer more from osteoporosis, bone tissue damage. I don't know what caused it – maybe they started drinking a lot of soda, and carbon dioxide washes out calcium. So, with fractures, prosthetics are required, very painful procedures. Approximately twenty–five percent of implants are rejected - a second operation is needed, which, you know, is even more painful.
Titanium is considered the best material for implantation: it is biocompatible and durable. But all the same, a prosthesis is a piece of heavy metal that is shoved inside a living organism. Nanostructured titanium is stronger than usual, so implants made of it weigh less and damage the bone less.
Nature has arranged it so that stem cells migrate to the fracture site, gradually forming new bone tissue there. In the case of a prosthesis, the tissue should grow on top of titanium, but it does it quite poorly, since it has never encountered titanium in its evolution.
The goal of the Lunin project is to "teach" cells to accept metal as a natural bone. To do this, the correct relief is made with two types of depressions. In the macrorelief, the depressions are 10-100 microns in size, so that the cell lies there like a ball in a hole, in the microrelief they are nanometer–sized, so that the cell can launch its processes and gain a foothold.
Then this relief is covered with the same composite material. The composite is similar in composition to our bones – collagen and hydroxyapatite (a calcium compound).
– The problem was to come up with glue to keep the composite on titanium, – says Alexander. – We took the plates, applied the solution, and then put them in water and put them on a rocking chair. In the first experiments, everything was washed off in an hour – in water, and now we put it in blood serum for a week – and this is a very aggressive environment – and nothing holds.
Lunin says that this is the first know-how of the laboratory – to figure out how to glue the composite to the prosthesis.
But the main know-how, of course, is different – stem cell growth factors.
Stem cells can transform into any tissue of any organ. And the dream of doctors is to use them to renew the parts of the body damaged by life. For example, to treat a scar from a heart attack, heal burns, restore islet cells that produce insulin, and so on. There are two ways here. The first is to remove human stem cells, multiply them in a test tube, and then inject them into damaged tissues again. The second way is to activate and attract the body's own stem cells. For this purpose, so–called growth factors are used, by chemical nature - proteins.
Growth factorIn the room where Zoya Galushkina works, there is a delicious smell of agar.
In general, if there is no smell of heated nutrient media anywhere in the genetic engineering laboratory, then the work is worth it. In old institutions, this smell has been ingrained in the walls for decades and is present everywhere, starting from the lobby.
Zoya Mikhailovna sows bacteria for growing in large quantities – a procedure that has probably been known since the time of Pasteur: we calcine a wire loop on a burner, make a smear on a bacterial colony in a Petri dish, lower the loop into a flask with a nutrient medium. We put the flask on a mechanical rocking chair at a temperature of 37 ° C, where it will swing for a day, the medium will mix, and bacteria will multiply. Together with the bacteria, the human cell growth factor gene embedded in them will also multiply. Thanks to this gene, bacteria will begin to synthesize the factor. In fact, we use bacteria as factories of biological substances.
The body produces growth factors in order for the right tissue to grow from stem cells in the right organ. Dozens of factors are now known, but very few are used in medicine.
Several types of factors are supposed to be used in the laboratory project. The first ones will attract stem cells to the damaged area. The second is to stimulate them to fix on the surface of the prosthesis. Still others are necessary for cell growth. The fourth – and most important – are differentiation factors, those that "convince" stem cells to transform into bone tissue. And in order for these bone tissue cells to multiply, bone morphogenetic protein is applied to the prosthesis.
– And how are you going to link all this into one? I asked Vladimir Lunin.
– This is the right question. You know, growth factors have already been tried to be used for healing, but the results were not very good. The fact is that these molecules are quickly washed out: they are small in size. And we need some of them to be washed out quickly, and others to sit firmly on the surface of the prosthesis. But this is exactly according to the profile of the laboratory – we are able to "bind" proteins with various substances in different ways. As part of the composite, the factors will last as long as it takes for healing.
Thanks to the jellyfishEmbryonic cells of the renal epithelium fluoresce with bright green light under the binocular microscope.
The beauty is unreal – thanks to the green fluorescent protein, or, in simple terms, GFP, which is produced by jellyfish of the Aequorea victoria species. However, since it was adapted for the needs of cell biology, the genes of this protein multiply inside bacteria. Then they are inserted into the necessary cells, and by the glow of the protein they see what happens to these cells. This is how I am now observing the result of an experiment to attract human cells to balls covered with growth factors.
– We put the sample under the microscope, remove the usual illumination, leave the ultraviolet, – explains Amir Tukhvatulin, junior researcher, graduate student of the Laboratory of Molecular Biotechnology. – Only cells that carry GFP glow. See?
Then they will also check here how comfortable the cells feel on coated titanium plates. They say that when a cell just sits on the surface, it looks like a ball, and when it takes root, it spreads out.
The Laboratory of Molecular Biology is located in the same building of the Institute as the laboratory of biologically active nanostructures.
– Is the project handled only by your institute? – I ask a question, of course, to Lunin when we return to his office.
– Seven only official co-executors! In one place, titanium is processed, in another – prostheses are made for maxillofacial surgery, in the third - collagen, in the fourth – experiments are conducted on rats…
– And the financing? It's expensive, isn't it?
– We were allocated one hundred and forty million rubles for three years. How is the system working now? Every year, the Ministry of Education and Science collects applications from those who want to formulate competitive lots. Those applications that experts and officials like pass. Of course, not everything is so good and objective, but there is objectivity: those lots that solve some problems of the country have chances. An open competition begins. The one who formulates the lot is more likely to win, but not one hundred percent. And in the case of implants, by the way, by writing an application, we got head-on with the organization that formulated the lot. The projects turned out to be equal in strength and both are very interesting. We have a strong biological part, they have a metal part. In the end, they gave funding to both programs, signing us up to each other as co-executors.
...Outside the office window, white crystals fall on the lawns of the Gamalei Institute – a product of natural nanotechnology, described by Kepler in his treatise "On hexagonal snowflakes". Lunin tells me that in two years his laboratory should produce a full-fledged product ready for use. The production of the component base and the final drug should be organized, the first stage of clinical trials has been completed. And in the future – the use of the same technologies not only in implants, but also, for example, for piercing the femoral neck of elderly people – to strengthen bones.
Looking more broadly, the management of growth factors in medicine is one of the ways of almost any therapy. Of course, not the only one, but in combination with technologies that have not yet been invented. The second nature has already caught up with the first one in complexity and can collect its hexagonal snowflakes no worse.
Portal "Eternal youth" www.vechnayamolodost.ru16.02.2009