Chapter 531 Tissue engineering, on the feasibility of artificial bladder

Author: Riding a pig to dig a hole

Chapter 531 Tissue engineering, on the feasibility of artificial bladder

Kunshi, Sanqing headquarters.

Xue Shen was lying in front of the computer, his fingers flying, and the sound of clicking keyboards echoed throughout the office.

After a long time, he stopped, clicked the mouse with satisfaction, and sent a long email.

"After more than three months, the animal experiment of artificial blood vessels on pigs has finally been completed. The experimental report has been uploaded and is now waiting for clinical application in humans."

"Time flies so fast, one year has passed in the blink of an eye."

He looked at the calendar and saw that it happened to fall on the last working day of the year, and he couldn't help but let out a long sigh.

"Fortunately, the two major projects this year went very smoothly. President Wei should be very satisfied. The promotion and salary increase will probably be put on the agenda."

Xue Shen thought happily and couldn't help grinning.

Tuk-tuk-tuk!

Suddenly someone knocked on the door.

Xue Shen quickly stopped his smile, sat upright, and shouted: "Please come in."

A young man with a delicate face walked in, and through the thick spectacles, their eyes met.

A look of surprise flashed through Xue Shen's eyes, and a smile quickly appeared on his face: "Ding Bo, it's you. You're such a rare visitor. Please sit down."

Ding Mian sat down opposite and said hello politely: "Hello, Xue Bo. I have long admired your name. I am glad to meet you."

He didn't waste time and went straight to the point: "Everyone is engaged in scientific research, so I won't talk about those frivolous things. I heard that your artificial blood vessel project is making good progress? Has the animal experiment been completed?

"

Xue Shen thought to himself that he didn't mind the other party speaking directly, but the progress of the artificial blood vessel project was technically an internal secret. If it wasn't for the internal staff talking loudly, it could only have come from General Wei.

So he smiled slightly and said, "Yes, did President Wei tell you? My next step is to apply for clinical trials."

Ding Mian slapped his thigh and was very happy: "Great, that means this project is very successful. It seems that I came to the right place this time."

Xue Shen chuckled and said, "You seem to have not explained your purpose of coming."

Ding Mian came over and said with excitement: "You should know about my stem cell laboratory. I had an artificial blood project before, and it was launched by the end of the year. It is almost completed."

"Then I was thinking about what I should do for the next project. Mr. Wei gave me a few words of advice, which immediately cleared the air and made me enlightened."

"He said that artificial organ transplantation is inseparable from nanotechnology. It just so happens that the artificial blood vessel project you are working on is also an artificial organ. If I have any ideas, I can come over and discuss it with you. Maybe there will be new gains."

"As soon as I heard about artificial blood vessels, an idea suddenly flashed in my mind, and the next project was immediately planned."

Xue Shen knew that the other party was an expert in stem cell research and had successful projects on his hands. He was not a mediocre person. He immediately asked: "What new project? Is it related to artificial blood vessels?"

Ding Mian did not answer immediately, but asked: "How much do you know about tissue engineering?"

Xue Shen slowly shook his head: "I've heard of it, but I haven't majored in this field, because I'm from physics, so I can't compare with your biology major."

"Then do you know the different stages of development of artificial organs?" Ding Mian continued to ask.

Xue Shen spread his hands and looked at him with a smile.

Seeing this, Ding Mian stopped asking questions and continued talking.

"You know, currently in the scientific community, fully functional manufacturing of the most complex human organs is still an unreachable goal, but great progress has been made in the construction of many special tissues."

"The holy grail in the field of artificial organs is to create solid organs like hearts, kidneys, lungs and livers."

"Then there are hollow, non-tubular structures like the bladder, which are at the next level of difficulty."

"If the difficulty goes down further, it is to create tubular structures, such as blood vessels and trachea."

"As for the simplest organs that humans can create, they are all flat and relatively hard, such as skin and corneas."

Xue Shen nodded: "So what you want to say is? We have created an artificial blood vessel, which is the third level of difficulty."

Ding Mian waved his hand and said: "Actually, the difficulty is not divided like this. Solid organs and tubular structures look very close, with only one level in between. However, the difficulty between the two is far greater than people think.

It could be the difference from 0 to 1."

Xue Shen asked with great interest: "Then what are the key difficulties between them?"

Ding Mian's face became serious and he said thoughtfully: "This involves the knowledge of tissue engineering."

"Perhaps when most people hear this name, they think it is a management or engineering term, but it is indeed a biological term."

"The tissues here refer to multi-layered human tissues, such as nano-scale proteins, micron-scale cells, millimeter-scale blood vessels, and centimeter-scale internal organs, which eventually grow into the entire body."

"Tissue engineering refers to analyzing the tissue structure and reconstructing human tissues through physical and chemical methods."

"In human tissue, cells are arranged in very complex ways, forming more or less symmetrical three-dimensional structures."

"In most cases, they are embedded in a complex network of active nanostructured 'cables,' a scaffolding of proteins that we call the extracellular matrix."

"The extracellular matrix provides an environment with structural, physical, mechanical, and biochemical properties that support cell growth and interactions within tissues."

"These extracellular matrices are an active gel secreted by cells and contain a large amount of fibrous proteins and sugars, including collagen, elastin, hyaluronic acid and proteoglycans."

"When we encounter injury, the extracellular matrix is ​​destroyed. When the cells move to the location of the trauma, the information in the extracellular matrix has disappeared, so the cells will produce scar tissue to fill the gaps. These scar tissue will be harder.

And it’s inconsistent with other structures.”

"Long ago, people realized that in order to grow human tissue, they had to create artificial scaffolds to grow cells, thereby recreating the environment originally provided by the extracellular matrix."

"This artificial scaffold must have the right structure to allow cells to attach to it, survive, evolve and divide."

"It must also be biocompatible and able to transmit physical and chemical signals to guide cell differentiation."

"For example, the human body's skeleton is a special scaffold woven from collagen and other fibrous proteins, where mineral calcium phosphate salts can precipitate to form hard bones."

"Bone fuses proteins and minerals at the nanoscale to achieve its special mechanical properties. It is both strong and elastic at the same time. It can resist damage and cracks caused by enemies or accidents, and prepares for growth and rebirth.

Prepare."

"This is the secret of being able to repair and heal after a broken bone."

"From this, artificial bone graft materials, artificial skin, etc. have been developed."

"These cases represent the emergence of a new discipline, which is tissue engineering."

"The ability to manipulate pluripotent stem cells to differentiate into any desired tissue is the ultimate goal pursued in this field."

"However, humans are currently unable to do this and can only settle for the next best thing. However, it is also very difficult to use artificial scaffolds to construct fully functional tissues."

"There are two main difficulties."

When Ding Mian said this, he coughed twice, picked up the tea brought in by his secretary, and took a big gulp.

Xue Shen listened with rapt attention and kept urging: "What's next? Go on."

"One of the main problems is that diffusion of nutrients and oxygen in artificial structures is very difficult to achieve."

"This means that it is feasible to construct functionalized small cell structures of a few microns. In fact, we have also developed such miniature human tissue structures, called organoids."

"But it's difficult to make them larger while remaining active because oxygen and necessary nutrients cannot reach the cellular level."

"Delivery in real tissues is achieved by a very complex combination of biological and physical mechanisms, including the formation of blood vessels, which can continuously deliver oxygen and nutrients to cells in a very dense environment."

"Delivering nutrients to cells and removing waste products is only possible when the distance between cells and capillaries is less than 200 microns."

"So, the formation of blood vessels in artificial organs has always been a thorny biological and engineering problem."

"Another difficulty lies in finding a suitable source of cells to provide a sufficient number of cells to ultimately generate large-scale tissues with medical significance."

"Currently, most artificial organ transplants have a donor, usually a deceased person, because this does not require strict matching."

"Scientists take the donor's organ, remove the donor cells on it, leave a tissue scaffold, and then implant the recipient's cells, so that a transplant can be completed."

"Over time, the donor scaffold will degrade in the body, and new cells and blood vessels will grow, completely forming a new organ."

Xue Shen couldn't help but interjected: "It's like an artificial blood vessel."

Ding Mian nodded and concluded: "Yes, so now the difficulty of artificial organs is very clear."

"First of all, we cannot use stem cells to develop a complete solid organ from scratch, whether it is a heart, kidney, or liver."

"So, we can only create an artificial scaffold, which can be made of biological materials, polymer materials, metal materials, or even obtained from the organs of dead people or animals."

"Next, we transplant the cells we need, which can be nerve cells, cardiomyocytes, retinal cells, or any other cells."

"Then we got stuck here because we didn't have a lot of cells to make the organ as big as a real organ."

"Perhaps this can be solved using pluripotent stem cell differentiation technology in the future. Anyway, I am still confident."

"If this difficulty is solved, we can culture a large number of cells, all coming from the same receptor, so there will be no immune response, and the conditions will be perfect."

"Next, we encountered a fatal difficulty, that is, the artificial organ has no blood supply. All the cells are clustered together and grow comfortably in a network composed of extracellular matrix, but without nutrients and oxygen arriving, they quickly

will die."

"There is no solution for this yet. Some relatively simple small organs can be connected to people's arms or thighs and use the body's own growth ability to grow blood vessels and nerves to solve this problem."

"But for large organs, there is still no solution."
To be continued...