3D Bioprinting — Could we ever 3D print a fully compatible organ and transplant it?

Key facts about 3D Bioprinting

  • 3D bioprinting consists of adapting the 3D printing technology to print tissue-mimicking constructs.
  • What drives this technology is to print human tissues and organs that can be used to replace our damaged ones.
  • The main problem at the moment is to ensure that these bioconstructions remain alive and functional once printed.


Bioprinting is the merge of two technologies: 3d printing and cell biology. This fast-growing emerging technology has open many possibilities in the field of regenerative medicine and tissue engineering.

This variation of the 3D printing technology uses bio-inks to create biological structures. The main purpose of this technology is to combine cells, growth factors, and biomaterials to fabricate tissue-like constructs that can later be used for clinical and biomedical applications.

A broad range of biomaterials has already been printed. The key is bio-inks.

Bio-inks are mainly cells embedded in a gel-like scaffold. This substrate, which may be organic or synthetic in nature, provides support for the cells to adhere and grow.

How works?

In general terms, bioprinting work very similar to the normal 3D printing. It consists of three steps, pre-processing, printing and post-processing.

First, the desired structure is defined in a digital model. Normally, the geometry to be bioprinted is reconstructed from computer tomographies or magnetic resonance images (MRI).

Second, the object is printed by depositing layers of biomaterial following the digital model.

Third, post-processing usually involves placing the bioprint in a special chamber so that the cells can mature properly and become a functional tissue. This step is, in fact, the main difference from normal 3D printing. Bioprints are living structures, which means that cells need a proper environment with oxygen, nutrients and space for waste disposal.

Printing techniques

Currently, there are several techniques to deposit these cell-rich bio-inks. Each technique is more appropriate for certain types of biomaterials than for others.

Inkjet bioprinting acts similarly to a common office inkjet printer. The bio-ink is pushed through nozzles in a continuous or drop-on-demand manner. The amount of bio-ink deposited in the substrate is controlled by heat or vibration. These bioprinters are more affordable than other techniques but are limited to low-viscosity bio-inks.

Extrusion bioprinting uses pressure to force the biomaterial to flow out of a nozzle. This technique has two advantages. First, bio-inks of different viscosities can be printed by adjusting the pressure, which means that highly viscous hydrogels can be printed without the need for high temperatures. Second, the technique can likely be scaled up for manufacturing, although may not be as precise as other techniques.

Microvalve bioprinting has similarities with the inkjet and extrusion techniques. Biomaterial stored under constant pneumatic pressure is delivered in droplets by the opening and closing of a mechanically, electrically or magnetically controlled microvalve. The printing process can be continuous or drop by drop and works well with low viscosity bio-inks.

Laser-assisted bioprinting moves cells from a solution onto a surface with the help of a laser. The laser heats a specific part of the solution creating a bubble that guides cells towards the surface. This technique is very precise and can be used for highly viscous biomaterials. The problem is that the heat from the laser may damage the cells. Furthermore, the technique is difficult to scale up to print large quantities thus has not been explored extensively as a biofabrication approach.

Tissue fragment bioprinting leverage the intrinsic capacity of closely spaced tissue fragments to fuse together, known as tissue fluidity. Therefore, tissue fragments containing several thousand cells are deposited in close spatial arrays so that they self-assemble.

Here, only the most relevant techniques are mentioned, but in this fast-growing field, new approaches are continuously being tested.

Potential applications

Printing tissues and organs has more applications than you can imagine at first glance.


With the increase in life expectancy and raise in chronic illnesses, exist an enormous gap between organ demand and supply.

One of the promising applications of this technology is the ability to 3D print tissues and organs to replace our damaged ones. The advantage of this method is that it reduces the risk of rejection since the transplantable bioprinted organ will be created form our own cells.

For now, relatively homogenous tissues like cartilage, skin, blood vessels, vagina, urine tubes and bladder have been bioprinted and transplanted in the lab or in clinical trials, but as the technology matures more complex organs are expected to be manufactured.

Also, the living bioprinted materials can be used in tissue engineering and regenerative medicine not only to replace damaged tissues but also to improve biological functions, as is the case with CRISPR technology.

Drug discovery and product testing

Another potential use of bioprinted living materials is in the area of medical testing and drug discovery.

Bioprinted tissues simulate their native microenvironments, such as cell type and tissue microstructure. Thus, bioprints are a good alternative for in-vitro model testing for preclinical test of drugs and cosmetics.

It is foreseeable that this application will be used on a commercial scale prior to organ transplantation as the requirements are lower than the characteristics necessary for its use in the human body.

Skin bioprinting is one of the most promising examples of bioprinting for several applications, such as the development of topical drugs, wound healing studies, and dermal toxicology research.

History and future

Bioprinting technology is the result of advances in many fields, from computing to printing and cell biology. It is difficult to determine a specific date for the birth of this technology although it would be relevant to highlight two important basic advances for this technology: the discovery of stem cells in 1978 and the invention of the 3D printer in 1984.

During the 1990s, medical researchers began to show interest in the idea of printing biological structures.

In 1999, the first lab-grown organ was implanted. The bladder cells were grown on a synthetic scaffold.

Since then, the medical field has begun to develop the bioprinting technology thanks to the advances in 3D printing and cell biology.


There is a huge gap between the demand and the supply of organs for transplantation. This technology is hope for solving this problem. The goal is to print the organs and transplant them in a few hours, without rejection from the body. These printed organs will be created from the same cells of the body of the person being transplanted, matching the exact size, specifications and requirements of each individual patient.

At present, fully functional 3D bioprinted complex internal organs are not feasible, but at the rate of current progress in the field, it could be possible in 10 years.


3D bioprinting opens new avenues in the field of personalized medicine. It is a promising technology that can finish the problems of finding a compatible donor. There are no surgical challenges, only technological ones.

Real organs

One thing is to print a tissue structure with the shape of an organ and other is make the organ fully functional. Organs are quite complex structures, they have multiple cell types, blood vessels, nerves, filtration system, and they are strong and durable.

For now, researchers have been able to bioprint many different tissues and organs, but not so many survive more than a few days. There is an urgent need to developed innovative solutions for the vascular networks that provide cells with nutrients and oxygen to grow and develop.

Bioprinting techniques and bio-inks

The current bioprinting techniques have still many limitations. Only certain types of bio-inks can be printed with a limited range of viscosities and limited precision.

In addition, the printing process has the potential to damage cells, as they only thrive within a narrow range of temperature, pressure and oxygen level.

This is a very young technology in rapid development. In the coming years, we will see how all these problems are solved.

4D bioprinting

The next step in this field is to print tissue with the ability to respond to stimuli, for example, heat or pressure, know as 4D bioprinting.

The changes can be in shape, such as deforming, twisting or growing or in function, such as cell differentiation or change in cell polarity.

This is the future indeed. Now, the 3D bioprinted objects are very basic, but we are starting to create more sophisticated multimaterial, multimodal biostructures.


Now it is your turn.

  • Would you accept a 3D bioprinted transplant?
  • What do you think about bioprinting tissues and organs for drug testing?

Leave us your opinion in the comments.

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  1. Biofabrication: an overview of the approaches used for printing of living cells — Scientific study
  2. 3D bioprinting of tissues and organs for regenerative medicine — Scientific study
  3. 3D bioprinting of organs — Youtube video

CRISPR — Is there any good reason to edit an organism’s DNA?

Key facts about CRISPR

  • CRISPR is a cost-effective technology to edit the organism’s DNA easier than ever before.
  • It was adapted from a natural bacteria defence system.
  • The gene drives alternative makes possible to pass edited genes to offspring.


CRISPR is a technology that allows altering DNA sequences and modify gene function faster, easier, cheaper and more precise than previous genome editing methods.

DNA is a molecule which carries the instructions of how a living organism should growth, develop, function and reproduce. DNA functions as a storage device of biological information and RNA function as a reader that decode this information. The technology to modify these molecules is called genome editing.

There were several recognised genome editing methods before, but CRISPR has revolutionized the field. The reason for such a revolution is its simplicity, versatility and precision. CRISPR stands for “clusters of regularly interspaced short palindromic repeats”. The key words here are “interspaced” and “repeats”.

How works

The term CRISPR was used for the first time in 1990 to refer to unknown repeating sequences observed in different bacteria DNA. Later on, scientists found out that indeed these sequences are part of the bacteria immune system. When bacteria defeat a virus after a viral infection, they chop the virus DNA and store it in their own bacteria genome in CRISPR spaces.

The bacteria use these pieces of information to defend themselves from future viral attacks.  Whenever a new viral infection occurs, the bacteria produce an enzyme (Cas9) that check if the new attack match with the pieces of RNA viruses already stored. When the enzyme finds a match neutralize the virus by destroying that part of the genetic code.

Now scientists have figured out how all these mechanisms are triggered, and we can engineer the whole process to edit any genome sequence. In short, the CRISPR technology works like a pair of molecular scissors where only two components are needed: a guide RNA and the Cas9 protein. First, a specific gene is target base on RNA-DNA base pairing. Second, the gene is cut through the enzyme activity (Cas9). Third, a new sequence of engineered DNA can be added by using the cell’s own DNA repair machinery.

In that way, pieces of genetic material can be added, altered or deleted, easier than never before. With the current levels of efficiency, the use of gene editing methods for therapeutic use is a realistic future scenario.

Potential applications

CRISPR is a very young technology. For now, it has been used only in research labs. However, it opens so many possibilities that many pharmaceutical and biotech companies are investing in this technology. There are many potential applications of this technology, but all of them fall in three main branches: agriculture, industrial biotechnology and human health.

The most direct application of CRISPR-technology is to study the genes function. Thanks to the human genome project, since 2003, we have identified all the genes in the human DNA, but we do not know yet which is the function of each of them. Since CRISPR is very precise, scientists can rapidly delete individual genes and analyse which traits are affected.


Another application within reach is to improve crops. With a technology like CRISPR, it is possible to make fruit more tasty and nutritious. But not only that, it is also potently possible to remove the allergens from peanuts or improve drought tolerance. Even create hornless dairy cows.


Scientists are also working on correcting genetic defects and stopping genetic diseases. Although there is still a long way before seeing the first tests in humans, several research projects are seeking to erase genetic diseases like hypertrophic cardiomyopathy or HIV. In addition, CRISPR technology is a powerful tool to develop new drugs in a faster and cheaper way.


Finally, this technology could be used to modify entire species by using gene drives. These are genetic systems, which increase the chances of a particular gene passing on from parent to offspring. In this way, an altered gene can be spread through entire populations very fast. This is interesting for example, to make mosquitos more resistant to the malaria parasite, preventing its transmission to humans, to eradicate invasive species or to reverse pesticide and herbicide resistance.

History and future

In 1987, a group of researchers reported the existence of repeated sequences of DNA without purpose known in a specific type of bacteria. In 1990, the same sequences were observed in very different bacteria and the sequences were named as CRISPR. Following investigations, found that these sequences were virus DNA, and they formed part of the bacteria immune system.

By 2011, scientists puzzle how all this immune system works and in the following year, the final breakthrough was reached. Scientists discovered how to engineer all this bacteria defence process to edit any genome at any place they wanted. Although the understanding of the whole mechanism was conducted by separate research groups, 2012 is considered the official year of discovery of this technology as a genome-editing tool.

Since then, research using this technology has exploded to optimize it and make it more efficient and accurate. Much research is still needed to understand the full implications of this technology in more complex organisms.

It is foreseeable to see the first applications on agricultural products although the biggest challenges will be to handle this technology to one day been able to edit the human genome.


During the past decade, technological breakthroughs in genome editing have moved the primary research goal in biotechnology from treatment to modification and cure, bringing gene therapy and precision medicine into a new era. CRISPR is easier, faster and about four times more cost-effective than the previous best genome-editing tool, known as TALENs. That has accelerated the pace of scientific research in this field. However, there are still many challenges to deal with and new ones have arisen.


So far, scientists have performed most of the genome editing research on cells and animal models and have demonstrated that the technology can be effective in correcting genetic defects. But there are several hurdles before to start safe clinical trials on humans. CRISPR has an accuracy of about 70%. That means that there is a 30% probability of unintentional modifications of non-targeted genes. This can lead to the introduction of unintended mutations like the creation of a new disease. That is why many experts argue that experiments in humans are premature.

Gene drives and germline editing

Another uncontrolled potential risk is the use of gene drives, in the case of spreading beyond the target population passing to other organisms through crossbreeding. Furthermore, the use of this technology in mass rise problems that go beyond the biology, political and governance problems.

A variant of the gene drives is the germline editing, which consists in modify genetically human embryos and reproductive cells such as sperm and eggs. Such application will raise problems in off-target effects and unintended consequences for future generations, but also ethical and legal challenges. To address these concerns, the National Academies of Sciences, Engineering and Medicine have published a report with guidelines and recommendations for germline editing.

The ethical concerns go beyond the technological challenges, but in any case open interesting debates about if we should make changes that could fundamentally affect future generations without having their consent, or the opposite case, if it is ethical to not modify the genes to cure potential diseases of future generation even when it is in our hand.


Now it is your turn.

  • What do you think about the idea of editing the DNA of an organism?
  • How far do you think we should go with this technology? Only to cure genetic diseases or there is no threshold for human enhancement, for example, to design taller and smarter humans?

Leave us your opinion in the comments.

Follow new articles

If you want to receive the new articles directly on your inbox, sign up for the free newsletter.


  1. History of CRISPR — Scientific study
  2. Applications of CRISPR technology — Scientific study
  3. Guidelines and recommendations for clinical trials for genome editing of the human germline — Report
  4. Human Genome Project — Website
  5. TALENs — Scientific study