Intervertebral Disc Tissue Engineering: A Literature Review

Kelly A.* and Wallace S.*, Hannah L., Krussig M., Mercuri J.

* Authors gave an equal contribution and are arranged in alphabetical order.

Abstract

Intervertebral Disc Degeneration (IVDD) leaves patients in pain and looking for relief which the current palliative treatments fail to provide. Intervertebral Disc Tissue Engineering (IVD-TE) aims to solve this by creating scaffolds to restore native IVD function. The objective of this literature review was to summarize the current research in IVD-TE. This review highlights the importance of IVD degeneration due to the vast socioeconomic burden and pain that one can experience. There are currently several methods of replicating the nucleus pulposus, including natural, polymeric, and hybrid hydrogels. Other exciting research aims to create annulus fibrosus biomaterial, hydrogel, and hybrid scaffolds which contain growth factors (GFs). Next, these methods can be combined to engineer a composite IVD and replace the entire IVD as a single unit. Finally, several research directions were proposed, including further collaboration between researchers, culturing under dynamical mechanical or hypoxic conditions, and utilizing crosslinking.

 

Objectives

  1. Acquire an understanding of intervertebral disc (IVD) physiology and pathophysiology.
  2. To develop a better understanding of what biomaterial scaffolds are currently being researched for Tissue Engineering (TE) the Nucleus Pulposus, Annulus Fibrosus, and Composite IVDs.
  3. Propose future research directions for the field.
  4. Creating an informational document for incoming members of the CI to provide background and training.

Physiology and Pathophysiology (1)

  • IVD degeneration is associated with Lower Back pain and herniations, as seen in many elderly individuals.
  • This can cause pain, herniation, and a variety of neurological problems. Tissue Engineering can solve those problems when other methods fail to.
  • The IVD is composed of 3 main parts: the Nucleus Pulposus (NP), the Annulus Fibrosus (AF), and the Cartilaginous Endplates (CEP).

Biomaterials in the Field (2)

  • The Creative Inquiry students learned about the biomaterials employed in IVD-TE, namely synthetic polymers, xenogeneic scaffolds, hydrogels, and cell based methods.
  • The literature review discusses the advantages and disadvantages to each of these scaffold biomaterials.

Directions of Future Research (3)

Based upon our research, we would advocate:

  • The use of hybrid methods.
  • More closely approximating the native disc microenvironment.
  • Using crosslinking in moderation.

Use of these Advancements (4)

  • The creative inquiry group conducted a literature review of over 140 sources during the summer.
  • The poster and literature review will be used to educate future creative inquiry students.
  • The students are working towards a publication in a high impact factor journal.

Real Life Scaffolds

An AF scaffold made by Du et al. in 2019.

An example of AF scaffolds employed in the field.

OrthO-X AF Repair Patch to help restore native physiology after herniation.

Herniation of the NP out through an annular defect.

An example of an NP Hydrogel.

OrthO-X NP Constructs which are crosslinked to improve mechanical properties.

A Composite IVD scaffold made by Du et al. in 2019.

A Composite Disc made by Hu et al. in 2018.

OrthO-X Composite Disc Constructs.