The use of regenerative medicine in fields such as injury recovery or disease or tumour treatments caused an authentic paradigm change in the way medical interventions were proposed. The aim was not only healing the damage but recovering the affected area to reach the conditions it had before the injury. The multidisciplinary work of physicians, scientists, biomedical engineers, or biologists allows us to understand the complex interactions between cells, scaffolds, signalling mechanisms, or bioactive factors to develop therapies for bone fractures, cancer treatments, or the regeneration of a damaged nerve or tendon.

However, in spite of all the laboratory work carried out, there is still a lot to do. The use of a myriad biomaterials has paved the way to historical advances in regenerative medicine. We still need to deeply understand the diversity of biological processes accompanying the tissue and organ regeneration. All the experts agree on stating that most of the main ways of human tissue recovery are still unknown. Besides, the current investigation is often focused on in vitro cases that shouldn’t be immediately transformed into in vivo situations without the previous performance of appropriate studies. 

Current Challenges for Biomaterials

The use of biomaterials in regenerative medicine has become a key aspect for a recovery that enables the reduction of injury load and, of course, the improvement of patients’ quality of life. These types of materials, which are able to partially or totally replace a tissue, organ or body function, are normally designed in the field of injury recovery with the aim of supporting and guiding certain cells in the recovery process of damaged tissues.

As we can assume, there has been a boom in the investigation of these types of materials recently. However there are still many uncertainties when developing a biomaterial and some problems about the generalization of obtained results might come up in very specific situations. For instance, in scientific literature there are studies that support the biocompatibility of a material in certain cases, but that doesn’t mean that it will work in a similar way under the conditions of our application. A successful tissue reaction must not be extrapolated to all cases without a previous individual test (and under conditions which are similar to the future real use).

In addition to this problem, there is a constant appearance of new biomaterials for regenerative medicine and the understanding of their biological response under clinical conditions is not in the spotlight. Finally, a biomaterial might have an excellent response to the needs it was designed for, but there are also other factors to be considered such as its user-friendliness or cost which are key when adopting it for daily clinical practice.

A Practical Example: Sterilisation

With the boom of the 3D printing technique, the possibility of printing personalised implants and using them in cases such as the ones contemplated in the TriAnkle project becomes very real. In the case a scaffold for such a purpose is created, not only the material biocompatibility must be taken into account, but also other factors such as pore size or some conditions that favour the vascularization and integration of the new tissue. Even its interaction with the sterilisation technique used can determine its final structure as it could be observed in a study carried out by Lafuente-Merchan and his team in 2021.

Researchers warned of the importance of evaluating the effect of different sterilisation techniques on common bioinks (biomaterials used for 3D printing). To study this, they decided to investigate their three most used modalities: autoclave, sterilisation with beta (β) and gamma (γ) radiation. The selected bioinks were NC-Alg (Nanocellulose-alginate) and NC-Alg-HA (nanocellulose-alginate-hyaluronic acid).

After conducting the experiments, the team proved that even though all the techniques were effective for the sterilisation on both biomaterials, their rheology (material capacity to warp or resist efforts), printability or physicochemical properties were better when using the autoclave. The analysis of these properties in the use of scaffolds also demonstrated that results were better on those manufactured with NC-Alg-HA since they become more suitable for tissue engineering and cartilage regenerative medicine.

This study is just an example of good practice when reflecting on the possible use of a biomaterial. The investigation in the laboratory is not only mandatory but necessary since we must know the isolated response of this type of materials to understand their individual characteristics. However, ignoring what still needs to be done to understand the way of working of these products in the clinical practice might be a costly mistake. Not only when thinking about resources, but also about our patients’ health.

Bibliography

M. Lafuente-Merchan, S. Ruiz-Alonso, A. Espona-Noguera, P. Galvez-Martin, E. López-Ruiz, J.A. Marchal, M.L. López-Donaire, A. Zabala, J. Ciriza, L. Saenz-del-Burgo, J.L. Pedraz (2021), “Development, characterization and sterilisation of Nanocellulose-alginate-(hyaluronic acid)- bioinks and 3D bioprinted scaffolds for tissue engineering”, Materials Science and Engineering: C, 126, 112160, ISSN 0928-4931, https://doi.org/10.1016/j.msec.2021.112160.