Emerging Trends in Biomaterials Research :

Across the broad spectrum of our field, biomaterials permeate nearly everything we do. Advances in biomaterials technology often have a ripple effect, and collectively, these advances elevate our entire field. Therefore, this special issue is focused on emerging trends in biomaterials ranging from the nanoscale to the macroscale, for a wide range of biomedical applications, including therapeutic delivery, immunotherapy, bioimaging, and regenerative engineering.

Traditionally, single component biomaterials have suffered from serious limitations due to limited control over biophysical and biochemical characteristics, hampering their utility for biomedical applications. To overcome these limitations, a range of advanced biomaterials are designed with multiple functionalities to guide cell behavior. This special issue emphasizes the design and development of the next generation of smart and responsive biomaterials to address these challenges. The original research articles capture the growing trend of functional biomaterials, and the review articles provide a critical evaluation of emerging trends in designing the next generation of biomaterials.

Engineering new biomaterials from natural sources such as marine sponges and decellularized tissues (cartilage) (Boccaccini, Detamore) are used to mimic biophysical and biochemical characteristics of native tissues. Other approaches include engineering natural polymers such as gelatin and alginate to co-encapsulate cells and therapeutics for guiding cellular functions (Mikos, Moshaverinia). Cell-instructive biomaterials are designed by incorporating biochemical clues to promote, augment, and facilitate regeneration of the damaged tissues (Burdick, Gu, Garcia, Bryant). These studies highlight that controlling cell-material interactions is necessary for modulating cellular functions.

“Smart” biomaterials are another emerging class of materials that respond to multiple external stimuli. For example, biomaterials responding to pH or cell-secreted enzymes can be used for on-demand and local delivery of therapeutics to regulate cell responses (Peppas, Segura). By utilizing the physicochemical characteristics of smart biomaterial, effective delivery of labile biomolecules is proposed for immunomodulation and long-term disease management (Mitragotri, Tasciotti). Smart and responsive biomaterials with multiple functionalities are promising biomaterials for a range of biomedical applications.

Nanoengineered biomaterials present significant opportunities to design materials with custom properties. By incorporating nanoparticles within a polymeric network, biomaterials with tailored functionality have been developed. A range of two- and three-dimensional nanomaterials have been shown to physically or chemically interact with the polymers, yielding new characteristics of the nanoengineered network (Sitharaman). Nanocomposite biomaterials with tailored functionality have opened up new possibilities for modulating cellular behavior for tissue engineering, localized drug delivery, and osteoarthritis (Sant, Zhang, Singh).

Advanced manufacturing technologies such as microfabrication and 3D printing enable mimicry of complex tissue architectures and can provide the essential cellular microenvironment to guide the formation of functional tissues. For example, microscale geometric patterning of ECM proteins can be leveraged to control cell alignment and differentiation (Feinberg). These microfabricated structures may be employed for in vitroapplications in toxicity screening, disease modeling and drug discovery. Another emerging approach to pattern and guide cell behavior is 3D printing. A vital aspect and bottleneck to the design and implementation of a bioprinting system is a lack of suitable bioinks that are printable and can guide cell functions (Gaharwar). To address these challenges, a range of advanced bioink formulations is designed including multicomponent systems, interpenetrating networks, nanoengineered bioinks and supramolecular networks.

Tissue Engineering applications in Therapeutic Cloning :

Few treatment options are available for patients suffering from diseased and injured organs because of a severe shortage of donor organs available for transplantation. Therapeutic cloning, where the nucleus from a donor cell is transferred into an enucleated oocyte in order to extract pluripotent embryonic stem cells, offers a potentially limitless source of cells for replacement therapy. Scientists in the field of tissue engineering apply the principles of cell transplantation, material science, and engineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues.

Porous Scaffold design for Tissue Engineering : 

A paradigm shift is taking place in medicine from using synthetic implants and tissue grafts to a tissue engineering approach that uses degradable porous material scaffolds integrated with biological cells or molecules to regenerate tissues. This new paradigm requires scaffolds that balance temporary mechanical function with mass transport to aid biological delivery and tissue regeneration. Little is known quantitatively about this balance as early scaffolds were not fabricated with precise porous architecture. Recent advances in both computational topology design (CTD) and solid free-form fabrication (SFF) have made it possible to create scaffolds with controlled architecture.

Biomaterials in future Healthcare :

Biomaterials are being used for the healthcare applications from ancient times. But subsequent evolution has made them more versatile and has increased their utility. Biomaterials have revolutionized the areas like bioengineering and tissue engineering for the development of novel strategies to combat life threatening diseases. Together with biomaterials, stem cell technology is also being used to improve the existing healthcare facilities. These concepts and technologies are being used for the treatment of different diseases like cardiac failure, fractures, deep skin injuries, etc. Introduction of nanomaterials on the other hand is becoming a big hope for a better and an affordable healthcare. Technological advancements are underway for the development of continuous monitoring and regulating glucose levels by the implantation of sensor chips. Lab-on-a-chip technology is expected to modernize the diagnostics and make it more easy and regulated. Other area which can improve the tomorrow’s healthcare is drug delivery. Micro-needles have the potential to overcome the limitations of conventional needles and are being studied for the delivery of drugs at different location in human body. There is a huge advancement in the area of scaffold fabrication which has improved the potentiality of tissue engineering. Most emerging scaffolds for tissue engineering are hydrogels and cryogels. Dynamic hydrogels have huge application in tissue engineering and drug delivery. Furthermore, cryogels being supermacroporous allow the attachment and proliferation of most of the mammalian cell types and have shown application in tissue engineering and bioseparation. With further developments we expect these technologies to hit the market in near future which can immensely improve the healthcare facilities.

Block your dates for the upcoming conference on World Congress on Advanced Biomaterials and Tissue Engineering held on October 17-18, 2018 @ Rome, Italy.  Theme of the conference is "Innovations in Biomaterials and Emerging Technologies in Tissue Engineering"

Adipose Tissue Repair : 

There is a clear clinical need for cell therapies to repair or regenerate tissue lost to disease or trauma. Adipose tissue is a renewable source of stem cells, called adipose-derived stem cells (ASCs), that release important growth factors for wound healing, modulate the immune system, decrease inflammation, and home in on injured tissues. Therefore, ASCs may offer great clinical utility in regenerative therapies for afflictions such as Parkinson’s disease and Alzheimer’s disease, spinal cord injury, heart disease, and rheumatoid arthritis, or for replacing lost tissue from trauma or tumor removal. the regenerative properties of ASCs that can be harnessed for clinical applications, and explores current and future challenges for ASC clinical use. Such challenges include knowledge-based deficiencies, hurdles for translating research to the clinic, and barriers to establishing a new paradigm of medical care. Clinical experience with ASCs, ASCs as a portion of the heterogeneous stromal cell population extracted enzymatically from adipose tissue, and stromal vascular fraction.

Organ-on-Chip:

Before any medicine can be brought to market, it has to be guaranteed it will not have any harmful effects on the person who takes it. To date health authorities require careful safety assessment, often involving animal models as well. The future, however, shows new ways to make the development of medicines better and faster, moving molecules from the lab directly to the patient. Organs-on-a-Chip technology is a new alternative way to screen drug candidates in a very early stage for efficacy and toxicity. The technology enables researchers to cultivate human cells representing organs under physiological conditions. Multiple organs can be placed on one chip and are interconnected to model the dynamics of a human organism. This is possible because 3D cell culture, micro-fluids and 3D printing technologies allow the cultivation of cells from patients

Tissue Regeneration: 

Tissue engineering (TE) is one of the biomedical technologies developed to assist the regeneration of body tissues to treat large size defects that are not possible to self-repair. TE may also help to substitute the biological functions of damaged organs by making use of cells. Although there is no doubt that cells are important for this purpose, an artificially created site to induce repair of the defect is a key factor for successful tissue regeneration.
This can be achieved only by utilizing an artificial scaffold of 3-dimensional structure for cell proliferation and differentiation as well as growth factors. Growth factors are often required to promote tissue regeneration. They also can induce angiogenesis which is required to supply oxygen and nutrients for the survival of the transplanted cells. However, one cannot always expect the biological effects of growth factors to be fully exerted because of poor in vivo stability, unless growth factor delivery technology is applied. This paper describes recent experimental data on tissue regeneration that emphasize the role of drug delivery technology in tissue engineering, briefly over viewing biodegradable polymers used for this purpose.

Protein-based tissue engineering in bone and cartilage repair:

Bioactive proteins signal host or transplanted cells to form the desired tissue type. Matrix systems are utilized to locally deliver the proteins and to maintain effective protein concentrations. For some indications, a matrix is required to define the physical form of the regenerated tissue. Substantial progress has been made in bone tissue engineering in recent years, based on the results of controlled clinical studies using bone morphogenetic proteins. Ongoing research in this area centers on the design of additional delivery matrices to expand the clinical indications, using synthetic delivery systems that mimic biological qualities of the natural materials currently in use. Although a similar rationale exists for the regeneration of articular cartilage with bioactive factors, advancement in this area has not been as substantial.

In-vitro cell expansion in Tissue Engineering:

In vitro has become an essential step in the process of tissue engineering and also the systematic optimization of culture conditions is now a fundamental problem that needs to be addressed. Herein, a rational methodology for searching culture conditions that optimize the acquisition of large quantities of cells following a sequential expansion process. In particular, the analysis of both seeding density and passage length was considered crucial, and their correct selection should be taken as a requisite to establish culture conditions for monolayer systems. This methodology also introduces additional considerations concerning the running cost of the expansion process. The selection of culture conditions will be a compromise between optimal cell expansion and acceptable running cost. This compromise will normally translate into an increase of passage length further away from the optimal value dictated by the growth kinetic of the cells. Finally, the importance of incorporating functional assays to validate the phenotypical and functional characteristics of the expanded cells has been highlighted. The optimization approach presented will contribute to the development of feasible large scale expansion of cells required by the tissue engineering industry.

Biodegradable Metals: 

After decades of developing strategies to minimize the corrosion of metallic biomaterials, there is now an increasing interest to use corrodible metals in a number of medical device applications. The term “biodegradable metal” (BM) has been used worldwide to describe these new kinds of degradable metallic biomaterials for medical applications and there were many new findings reported over the last decade. The recently-developed representative Mg-based BMs (pure Mg, Mg–Ca alloy, Mg–Zn alloy, etc.), Fe-based BMs (pure Fe, Fe–Mn-based alloys, etc.) and other BMs (pure W, pure Zn and its alloys, Ca-based and Sr-based bulk metallic glasses, etc.) were comprehensively reviewed with emphases on their microstructures, mechanical properties and degradation behaviors, in vitro and in vivo performances, pre-clinical and clinical trials. Moreover, current approaches to control their biodegradation rates to match the healing rates of the host tissues with various surface modification techniques and novel structural designs. BM belongs to “bioactive” biomaterials and its future research and development direction should lean towards “third-generation biomedical materials” with “multifunctional capabilities” in a controllable manner to benefit the local tissue reconstruction.

Hydrogel Biomaterials:

Hydrogels are water-swollen polymeric materials that maintain a distinct three-dimensional structure. They were the first biomaterials designed for use in the human body . Traditional methods of biomaterials synthesis include crosslinking copolymerization, crosslinking of reactive polymer precursors, and crosslinking via polymer-polymer reaction. These methods of hydrogel synthesis were limited in the control of their detailed structure. Due to side reactions the networks contain cycles, unreacted pendant groups, and entanglements. Other inadequacies of traditional hydrogels have been poor mechanical properties and slow or delayed response times to external stimuli . Novel approaches in hydrogel design have revitalized this field of biomaterials research. New ideas on the design of hydrogels with substantially enhanced mechanical properties, superporous  and comb-type grafted hydrogels  with fast response times, self-assembling hydrogels from hybrid graft copolymers with property-controlling protein domains, and from genetically engineered triblock copolymers are just a few examples of hydrogel biomaterials with a smart future.

Biodegradable polymers as Biomaterials

Biomaterials are used in prostheses and medical devices for different purposes. Polymers are the most diverse class of biomaterials. All biomaterials must meet certain criteria and regulatory requirements before they can be qualified for use in medical applications. Biocompatibility is one of the most important requirements. Both nondegradable polymers are designed to degrade in vivo in a controlled manner over a predetermined time. The main mechanism of in vivo degradation of polymers is ‘hydrolytic degradation’, in which enzymes may also play a role (i.e. ‘enzymatic degradation’). Both natural e.g., collagen, and synthetic e.g., poly(alpha-hydroxy) acids, biodegradable polymers are used in biomedical applications. Many of the current polymers and processing techniques need to be improved in order to produce polymers with better performance in biological media. An important trend in related research and development is the synthesis of novel polymers, which would exhibit improved biocompatibility, and be bioresponsive.