**Author details**

suspensions may also come about from the high shear stresses observed during ejection and

In many cases, the bioprinting process requires that before and during printing, cells and molecules must be carried in a fluid vehicle that shortly after printing requires consolidation and should consequently behave as a viscoelastic solid. This phase change must occur without damage to the biochemical, cells, or more complex units within the fluid, which presents a considerable challenge. Concurrently, tissue printed mustn't be too solid, or cell spheroids

Organ printing is a technology that promises to transform tissue engineering into a commercially successful biomedical industry. Unlike other tissue engineered approaches, organ printing involves the high throughput generation of organs, relying on automated cell sorters, cell and organ bioreactors and robotic bioprinters, most of them which are already commercially available [46]. However, much research is necessary to turn this technology into

**4. Conclusion: Tissue engineering — From the bench to the bedside**

It is known that any technology takes about 20 years to reach the market, and despite progress in many fields, this timeframe has yet to shorten [20]. Accordingly, tissue engineering, which has officially given its first steps during the late eighties, hasn`t brought many products to the

In contrast to biomaterials - which are readily available as hip implants, contact lenses, silicon breast prosthesis, among others –, and cell therapy – which is also available for bone marrow transplants, as well as its first allogeneic stem cell therapy products [21] -, constructs have been successfully produced for only few applications, largely limited to non-modular organs such as skin epidermis, corneal epithelium and cartilage [40]. Indeed, Apligraf - a bilayered skin substitute - was the first allogeneic cell based therapy to be approved by the US Food and Drug Administration (FDA), receiving permission for sale as a treatment for venous leg ulcers13. Apligraf is constructed by culturing human foreskin-derived neonatal fibroblasts in a bovine type I collagen matrix over which human foreskin-derived neonatal epidermal keratinocytes are then cultured and allowed to stratify [68]. Even though it is considered one of the first tissue engineering products ever approved for commercialization, Apligraf doesn`t directly restore skin, but transiently protects and provides injured skin with scaffold and signaling molecules (produced by the cells within the construct) which fosters and accelerate skin regeneration. Engineered bladders and airways have also been built and implanted *in vivo*, but as they require highly customized and complex approaches, they are available to a small number of patients, and are not considered products to be sold, such as Apligraf and other similar

Therefore, it is clear that, in spite of recent advances, tissue engineering has much to deliver. Innovative strategies, such as the presented in this chapter, present out of the box solutions

impact of a fluid drop [50, 51, 52].

reality of clinical application.

bedside [20].

products.

won`t interact and form a continued tissue.

308 Advances in Biomaterials Science and Biomedical Applications

Juliana Lott Carvalho1 , Pablo Herthel de Carvalho2 , Dawidson Assis Gomes1 and Alfredo Miranda de Goes1

\*Address all correspondence to: julianalott@gmail.com

1 Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Brazil

2 Department of Veterinary Clinicals and Surgery of the Federal University of Minas Gerais, Belo Horizonte, Brazil
