Literature Review On Periodontium Regeneration

Literature review on periodontium regeneration; Macrophage vs MSCs

Background and Literature Review

1. Introductory Statement.

Periodontitis is a chronic, non-communicable disease. Characterised by the systemic loss of both the soft tissue surrounding the teeth and the increased resorption of bone supporting them,(2) thereby creating a dysregulation of the supporting structures including; periodontal ligaments (PDL), alveolar bone (AB) and the cementum, thus leading to tooth loss (Figure 1).

Both the World Health Organisation (WHO) and the Centre for Disease Control (CDC) recognise periodontitis as a prodigiously prevalent disease, affecting 40-50% of adults aged over 30 years old worldwide (4). Sharing many of the same risk factors

The global cost of this disease has blown us to a staggering $54 billion/USD in lost productivity, in 2010 the direct and indirect costs surround periodontal disease, was the significant part of the(5) $442 billion/USD spent on oral diseases.

Over the last 30 years or so we have established a clear relationship between bone and the immune system, commonly referred to as Osteoimmunology (OI). There are two active immune systems in humans that can act on the development and maintenance of the skeletal system, not least the teeth.

As the major component of the following literature review and project investigation, we shall be focusing on the communication between the tissues of the periodontium and cells related to the immune system. Of particular interest, for the regeneration of the periodontium, we shall target the ability and effects of various guises of localised Mesenchymal stem cells (MSCs) and Macrophages (MΦ). Enough evidence to the benefit of employing these particular cells to the regenerative process have provided highly promising results.

Literature

In the 1960s Mackanes noticed the efficacy of MΦ against bacteria such as Listeria and Staph Aureus, instigating further studies that would eventually highlight the activation of MΦ.

Florence Loi (14)and her team investigated the use of various combinations of macrophage (MΦ) phenotypes, i.e., Naïve (Mϕ), proinflammatory, (M1) and anti-inflammatory (M2) macrophages (and their subcategories) co-cultured with the osteogenic properties of pre-osteoblasts. The design of the study was to demonstrate the malleability and heterogeneity that MΦ display, and how they contribute to osteogenesis. Several studies have begun to indicate there is more of a sliding scale for the functionality of these cells, more so than belonging to a fixed active state.

Polarisation and plasticity, controlling the physical state of MΦ lends itself to manipulation by way of cytokines or growth factors, allow us to steer the cells to express the most beneificial factor for the current conditions. MΦ can differentiate from peripheral blood mononuclear cells upon migration into the tissue, or they can generate from the from MSCs residing in the affected tissue region. There are two activation pathways classical and alternate, promotion of the M1 and the M2 phenotypes respectively as per the inducing agents below,