Tissue Engineering Scaffold

Tissue and organ damage or functional failure is a major problem faced by human medicine. Clinical treatment usually adopts surgical repair, tissue organ transplantation, artificial prosthesis implantation, mechanical device, and other schemes. To allow patients to rebuild, restore or compensate for lost functions to varying degrees. Although artificial organs and transplants have benefited many patients,

But it also revealed its fatal weakness: the former is incompatible with the human body and cannot establish advanced human functions; the latter has limited donors and has problems such as immune rejection.

With the progress of cell biology, molecular biology, bioengineering, and materials science, "tissue engineering" was born in the late 1980s and early 1990s, which opened up a new path for the rise of regenerative medicine.

Tissue engineering is the application of the principles and methods of engineering, life science, and materials science. The function-related living cells cultured and expanded in vitro are planted on porous scaffolds, and the cells proliferate and differentiate on the scaffolds to construct biological substitutes. It is then transplanted into the damaged tissue to achieve a science of repairing, maintaining, or improving the function of damaged tissue.

Tissue engineering involves growing new tissues in the laboratory, incorporating skeletons, natural tissue cells, and bioactive molecules to mimic the body's biological processes.

The tissue cytoskeleton has similar functions to the native cellular extracellular matrix (ECM). It provides the structural and material environment for cell growth, migration and response to signals, mechanical properties for the resulting tissue, and bioactive cues for the regulation of activity of resident cells.

There are three main strategies for tissue scaffolds that mimic native ECM function:

• Seeding of cells on porous scaffolds pre-prepared from degradable biomaterials including decellularized ECM from allogeneic and xenogeneic tissues, natural polymers, bioglass, and synthetic polymers.
• Seeding the cells in a petri dish with a thermoresponsive polymer coating and removing the polymer membrane after the cells are confluent
• Embed cells in a hydrogel matrix made of natural or synthetic polymers (such as 3D bioprinted bioinks), and the hydrogel simulates the natural extracellular matrix to promote cell proliferation and differentiation.

The core of tissue engineering is to build three-dimensional complexes composed of cells and biomaterials. Compared with traditional two-dimensional structures (such as cell culture), its biggest advantages are as follows:

• Form a living tissue with vitality, reconstruct the shape, structure, and function of the damaged tissue, and achieve permanent replacement;
• It can repair large tissue defects after a minimum amount of tissue cells (even obtained by tissue puncture) can be cultured and expanded in vitro;
• It can be arbitrarily shaped according to tissue and organ defects to achieve the perfect morphological repair. The proposal, establishment, and development of tissue engineering have changed the traditional treatment model of repairing wounds with damage and opened up a new way for the ultimate realization of non-invasive repair of wounds and functional reconstruction in the true sense, which is a revolution in the field of surgery.

Although tissue engineering research has only experienced a short development process of more than 30 years, it has completed a large number of basic theories, tissue construction, and implantation in animals. With the rapid development of cytology, molecular biology, and biomaterial research, great progress has been made in the research and application of tissue engineering in various tissues.

At present, commercialized tissue-engineered skin, cartilage, and other products have officially entered clinical application, and clinical applications of tissue-engineered bone, tendon, skeletal muscle, cornea, mucous membrane, and blood vessel, bladder, pancreas, genitals, kidney, liver, etc. A certain curative effect has been achieved, and tissue engineering technology, as an emerging biological high-tech technology, has broad application prospects.

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