The Food and Drug Administration (FDA), a regulatory agency of the United States recently released several documents to address the emerging and promising field of regenerative medicine. This covers the wide range of regenerative medicine from drugs, biologics, and medical devices but most of all, the potential to address serious conditions that will benefit from the future discoveries and pending therapies. Regenerative properties are not limited to being a result of genetic manipulation, it can be seen in a natural state. In examining factors responsible for regenerative properties in this natural state, limitations and capabilities of human cells have been identified. Stem cells, genetic manipulation, and bioengineering have been significant milestones in regenerative science but there are malicious opportunities that would take away from the overall contributions. For that reason, it is inevitable that the FDA has released guidance documents for this dynamic field. But aside from the many possibilities that pursuing regenerative medicines would have on providing patients with alternatives, it should be noted that the current treatment is quite limited.
The Food and Drug Administration (FDA), a regulatory agency of the United States responsible for public health and consumption recently released several documents to address the emerging and promising field of regenerative medicine. This covers the wide range of regenerative medicine from drugs, biologics, and medical devices but most of all, the potential to address serious conditions that will benefit from the future discoveries and pending therapies. Regenerative medicine seeks to address repair or replacement of damaged tissue and related advances in molecular biology (Mao and Mooney 2015).Historical Background
Regenerative properties are not limited to being a result of genetic manipulation, it can be seen in a natural state. Research has shown that amphibians exhibit full limb regeneration with no limitation on capacity or time. Stem cells in humans characterize the closest similarities in regeneration but are restricted by their versatility after a period of time. Although both amphibians and humans exhibit the ability to regenerate, the similarities are quickly changed to differences. For amphibians such as salamanders, regeneration first requires the formation of a wound epidermis and an apical epithelial cap to trigger cell migration. The signals that are essential in regeneration come from the apical epithelial cap, which release chemical signals for both migration and regression to occur (Muneoka et al. 2008).
The chemical signals responsible for regeneration also include a system in which fibroblast growth factors are involved to proceed with growing limbs. After the signals are released for cell migration, the specialized cells then regress back to being unspecialized to proceed with regeneration of the limb. Despite the inability to physically distinguish between an anatomic creation (intersegmental) and an anatomic addition (intrasegmental), regulations of both processes indicate signaling differences (Satoh et al. 2010). While the fibroblast growth factor regulates a complete formation, the bone morphogenetic protein regulates the necessary additions to a specific area of a body part.
Although human embryonic cells are also in an unspecialized state before developing limbs, the genetic information from the Hox gene assisting in regeneration is lost upon development while the salamander fibroblasts retains this genetic information (Muneoka et al. 2008). Another key difference is that although both salamanders and humans have an immediate response to injury with fibrosis, the main difference consists of a scar formation due to excessive extracellular matrix by the mammalian fibroblasts. In examining factors responsible for regenerative properties, limitations and capabilities of human cells have been identified.
Although human regeneration is primarily at a cellular level after development, blood stem cells retain their unspecialized state in bone marrow. Hematopoietic blood stem cells can differentiate into specialized blood cells (lymphoid, myeloid, and erythroid classifications) that make up the immune system as well as tissue cells (Parham 2014). Success hematopoietic cell transplants can be used in patients with immunodeficiencies or blood cancers to generate a normal immune system.
However, these procedures are not without graft-versus-host-reactions and therefore human leukocyte antigen (HLA) typing is pertinent to a successful implantation in stem cells (Parham 2009). HLA typing is used by the immune system to recognize pathogens and HLA mismatches can trigger a fatal immune response that can result in death. Nonetheless, even with additional procedures that are required for donation, the blood stem cells still remain in the unspecialized state and subsequent development of blood stem cell implantation that are seen naturally in the human body. These are the two characteristics that are studied in stem cell research, due to the dynamic field of continuous advances as well as novel inventions.
Innovative Research and Challenges
The focus of stem research has been on the acquisition of these stem cell in their most adaptable state and has not been without controversy. The Somatic Cell Nuclear Transplantation (SCNT) is a cellular fusion of a donor egg without a nucleus with donor cells containing genome of interest to create an embryo that is used for therapeutic cloning by harvesting embryonic stem cells (ESC) without maturation (Alberts 2008). This was a way to obtain the ESCs in the undifferentiated state using adult stem cells. However, the SCNT technique was used to create Dolly, a cloned sheep whose embryo was allowed to maturation and in a foster mother that had a fairly normal life despite shortened telomeres, was considered a trigger for challenging the notion of a differentiated state in an adult nucleus cell (Wilmut 2015).
SCNT allowed for viable embryos in both types of cloning using adult stem cells to create ESCs. Although donated ESCs from animals were used initially in research, researchers were able to finally derive human ESCs in 1998 (Godoy et al). At this point, it became a moral and ethical debate due to the source of human ESCs. These were obtained from discarded or donated human embryos and as a result of timing, ESC research were heavily regulated in the United States by President Bush in 2001 and ESCs were restricted to existing lines (Godoy et al). A more acceptable form would soon be discovered and utilized in research.
The method for induced pluripotent stem cells (IPSC) was discovered in 2006 and provided an alternative for stem cell research (Takahashi and Yamanaka 2006). Although this addressed the ethical questions in regards to embryonic stem cells, this did not fully replace the existing research. ESCs still have the advantage of not carrying the defective genetic material that IPSCs initially have prior to reprogramming as well as the costs that are associated with producing and modifying IPSCs (Cyranoski 2018). All three types of stem cells have their merits and weaknesses in research and having the knowledge from the different stem cell types have cultivated a greater progress in discovering and examining the nature of stem cells. In looking at the nature of stem cells, a key component requires the ability to manipulate the existing genetic material. Deoxyribonucleic acid (DNA) was once considered a challenging molecule to modify or work with, has now evolved into one of the simplest to manipulate in a test tube or organism and is known as genetic engineering (Alberts 2008).
The ability to isolate, replicate, and sequence DNA has allowed for even more discoveries in the scientific world. One resulting outcome is the emergence of gene therapy. The intent behind gene therapy is to potentially insert a modified gene instead of resorting to drugs or medical interventions (Clement 2017). As with any genetic changes, there are concerns regarding the risks of harmful mutations that can occur. Gene therapy has been used in a randomized phase IIB trial for cystic fibrosis patients (Alton 2016). Although additional research will be required to see the full impact of gene therapy, the modification of DNA is a pending therapy for the medical field to observe and analyze.
Given the natural state of regeneration and introduction to manipulation of DNA, this provides the basis for what is considered the next step in the medical field and the challenges that will be presented. With the right guidance, stem cells can be integrated with synthetic materials that can be utilized for tissue engineering that can repair damaged organs or to develop fully functional organs (Mao and Mooney 2015). Despite providing a solution or alternative for terminal or chronic diseases, there are risks that must be accounted for because of the potential for harm and exploitation of patients. There is the possibility that the benefits would be manipulated for a more sinister outcome.
Stem cells, genetic manipulation, and bioengineering have been significant milestones in regenerative science but there are malicious opportunities that would take away from the overall contributions. For example, there are organizations with no scientific research prey on vulnerable patients by promising a cure all. Genetic manipulation can also be used for bioterrorism by creating harmful mutations in bacteria or viruses, which can easily be the source of unforeseen maladies or potent diseases rivaling the worst of epidemics. Despite the best intentions for DNA editing to be a cure, the edits could be utilized as a bioterrorism weapon. In addition, the combination of stem cells and genetic engineering can also be used to create designer babies or human cloning. Designer babies would be chosen over their non-designer siblings would be in danger of being discarded and disadvantaged. This would also apply to human clones, especially if clones were exploited for their organs. As for the advances in bioengineering, this can also be abused for organ harvesting. In addition, with all of these potential issues being a factor in creating harm to patients, the most damaging would be include the lack of quality assurance which would impair the patient’s health even further. For that reason, it is inevitable that the FDA has released guidance documents for this dynamic field to maximize both safety of and efficacy for patients.
On November 16, 2017 in an official press release, the FDA acknowledge the current progression of the scientific world, the ability to create or manipulative cells and tissues are a reality and not a fantasy (FDA Press Release 2017). For that reason, the FDA released several documents to ensure that regulations allowed for a structured guidance in research while fostering innovation in a safe environment. With an emerging field that is constantly progressing, it was necessary to balance the safety and efficacy of research with groundbreaking discoveries. Two Final Guidance documents and two Draft Guidance documents were released to address regenerative medicine; concerning the Human Cells, Tissues, and Cellular and Tissue-Based Products (HCT/P), Same Surgical Procedural Exception, devices that are associated with regenerative medicine advanced therapies (RMAT), and expediting the approval process of RMAT. The FDA final guidance documents looks at both HCT/P as well as Same Surgical Procedural Exception, differentiating between different donor and recipient or the same donor and recipient relationship.
These guidance documents for HCT/P provide expectations on what modification or processing can be considered minimal manipulation, how HCT/P can be properly stored, and what properties must be present and uncompromised (Final Guidance: Regulatory Considerations 2017). It is essential that the HCT/P are able to retain original capabilities. Further guidance includes clarification on what homologous (donor and recipient) use includes and classification on both types of nonstructural (supportive, protective, or connective) tissue and structural (reproductive cells or, blood stem cells, or lymph nodes) tissues (Final Guidance: Regulatory Considerations 2017). While nonstructural is considered in tissue form, structural includes both cells and tissues forms. Accompanying this final guidance document is the exemption of hospitals from manufacturer registration and provisions if they are solely responsible for extraction and implantation of HCT/P in the autologous (donor and recipient are the same individual) use and only need to follow health care guidelines (Final Guidance: Same Surgical Procedure 2017).
Further requirement like the HCT/P, includes addressing circumstances in which extracted cells or tissues must still retain their original form despite minimal processing or storage. The Draft Guidance documents looks at both device and drug implications for regenerative medicine. When medical devices are used with or in addition to combination products with RMAT for recovery, isolation, or delivery purposes, it will be based upon the final product and examined accordingly for actual use and features. (Draft Guidance: Evaluation of Device 2017). The medical device itself will still abide by the same medical device guidelines for classification, clinical and commercial approvals as outlined in Title 21 CFR Part 800-1299 (CFR 2018). The medical device and combination product is likely to be a supplemental factor for RMAT therapies and treatment. Another guidance document can be seen addressing the expedited process for serious conditions with no or insufficient treatment with RMAT, looking at the confirmation of regenerative medicine therapy properties as well as early clinical evidence for potential effectiveness (Draft Guidance: Expedited Programs).
The drug approval designations are outlined by fast track, breakthrough, priority review, and accelerated approval as seen in Table. Additional sources of reference can be found in the following sections of the CFR in regards to rare diseases as well as serious conditions. Both HCT/P and devices with RMAT are further addressed in Title 21 of the Code of Federal Regulations (CFR) Part 1271 (CFR 2018). In a similar comparison, the requirements for orphan drugs are referenced in Part 316 and humanitarian use devices are referenced in Part 814 of the CFR, both addressing the current solutions to what can be done for existing conditions.
Discussion and Impact
In expanding the scope of drug, biologics, devices and combination systems to accommodate for regenerative medicine, this helps to refine emerging research to its best classification. However, there is an additional incentive for curing rare diseases by the FDA to accommodate for a non-profitable cause. In targeting an emerging treatment, there is a strong possibility to implement all the lessons from the past and to enforce a protocol and procedure that maximizes efficiency. By setting clear boundaries and expectations, the FDA is allowing for all research to move forward from an ethical and deliberate standpoint. The mission statement of the FDA indicates that the intention was to protect public health by prioritizing safety of consumers, confirming both efficacy and integrity of consumer products and medical therapies or treatments, but most importantly, addressing the evolving landscape of public health (FDA Mission 2018).
Regenerative medicine marks the opportunity to foster innovation in a transitional state. This shift from traditional molecular medicine and into integrative medicine marks an interesting nostalgia. Prior to the mass production of medications, doctors were treating patients with a case-by-case approach. The use of drugs, biologics and devices have been based on a majority-based approach while the intention and progress of regenerative medicine will be much more customized to the patient’s needs. The expectations from regenerative medicine may be the possibility of minimized complications, less invasive procedures, and ensuring a better quality of life. Aside the potential of providing patients with alternatives for their conditions, another aspect of regenerative medicine that should be examined is looking at where there may be overlap to address existing problems that have not yet accounted for or are currently rising to prominence.
Despite the many advances in medicines, antibiotics are affected by the lack of inadequate innovation and bacterial resistance. The World Health Organization (WHO) released a report reviewing the antibiotic research and clinical developments, current challenges such as drug development time as well as cross-resistance, and suggest that the future is in alternative therapies to successfully combat high priority antibiotic resistant strains such as tuberculosis, Staphylococcus aureus, and more (WHO 2017). For that very reason, the ability to utilize gene therapy may be a possible solution to eliminating resistant strains.
Viruses called bacteriophages can infect bacteria due to the recombinant mechanism that allows for insertion and integration into the host cell and subsequent exit to the next cell (Alberts 2008). However, the progression is not as immediate in recent studies. The WHO had biological agents as part of the novel research for antimicrobial defense but the impact of bacteriophages is still very speculative at this time (WHO 2017). However, the characteristics seen in bacterial antibiotic resistance and the recombinant nature of bacteriophages may present a need for managing mutations. Although bacteriophages infect bacteria, there should still be a concern for how humans are impacted. However, this could be a greater area of interest when gene therapy becomes more robust and applicable. Research in academia or industry that progresses to clinical to commercial will need these guidance documents and continuously search for the next breakthrough since this is an opportunity to look at all possibilities.
Given the new direction that regenerative medicine has taken and the inclination towards a personalized approach for the patient, the focus of medicine may have returned to a more humane approach when it comes to therapy and treatments. In fact, this progress could easily be a step in going beyond the prestige or profit of new discoveries and finding an even greater purpose in revolutionizing the world of medicine. This may be the start of finding an effective cure but this could also become an elimination of the existing diseases and lead to eradication of certain diseases.
Limitations and Conclusion
With any emerging technologies making a stronger impact as it evolves, the rules and regulations that apply are subject to change. The current landscape is full of potential but still requires a lot of thought. In having a structured approach before regenerative medicine has gained more prominence and application, the dedicated focus and hard work may result in better outcomes than in the past.