Abstract
The field of tissue engineering has tantalizingly offered the possibility of regenerating new tissue in order to treat a multitude of diseases and conditions within the human body. Nevertheless, in spite of significant progress with in vitro and small animal studies, progress toward realizing the clinical and commercial endpoints has been slow and many would argue that ultimate goals, especially in treating those conditions which, as yet, do not have acceptable conventional therapies, may never be reached because of flawed scientific rationale. In other words, sustainable tissue engineering may not be achievable with current approaches. One of the major factors here is the choice of biomaterial that is intended, through its use as a “scaffold,” to guide the regeneration process. For many years, effective specifications for these biomaterials have not been well-articulated, and the requirements for biodegradability and prior FDA approval for use in medical devices, have dominated material selection processes. This essay argues that these considerations are not only wrong in principle but counter-productive in practice. Materials, such as many synthetic bioabsorbable polymers, which are designed to have no biological activity that could stimulate target cells to express new and appropriate tissue, will not be effective. It is argued here that a traditional ‘scaffold’ represents the wrong approach, and that tissue-engineering templates that are designed to replicate the niche, or microenvironment, of these target cells are much more likely to succeed.
Highlights
This paper, and this journal issue in general, is concerned with sustainability in the field of tissue engineering
Dai and colleagues have worked with bovine collagen scaffolds, showing good results in a chronic spinal cord regeneration after injury (SCI) canine model when seeded with umbilical cord mesenchymal stem cells (Li et al, 2017), and in human clinical trials with both acute (Xiao et al, 2018) and chronic (Xiao et al, 2016) spinal cord injuries
This essay has shown, through a series of examples of attempts to regenerate tissues through a conventional scaffold approach, that any process that relies on biomaterials that have been determined to be biologically inert and, “biologically safe” is highly unlikely to succeed
Summary
This paper, and this journal issue in general, is concerned with sustainability in the field of tissue engineering. Biomaterials for Sustainable Tissue Engineering of selected target cells through a systematic combination of molecular and mechanical signals (Williams, 2006). The scientific factors largely relate to the ability to deliver those molecular and mechanical signals mentioned earlier, such that new tissue, with appropriate morphological and functional characteristics, can be generated and maintained. Within this complex milieu, the roles of, and effects on, the target cells, on the whole array of biomolecules and on the biomaterial templates all have to be considered. In order to determine how these templates have performed, and have contributed, either positively or negatively, to tissue regeneration, it is necessary to consider the clinical outcomes that have emerged
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