Three‐Dimensional Humanized Model of the Periodontal Gingival Pocket to Study Oral Microbiome

Abstract

The oral cavity contains distinct microenvironments that serve as oral barriers, such as the non-shedding surface of the teeth (e.g., enamel), the epithelial mucosa and gingival tissue (attached gingiva) where microbial communities coexist. The interactions and balances between these communities are responsible for oral tissue homeostasis or dysbiosis, that ultimately dictate health or disease. Disruption of this equilibrium can lead to chronic inflammation and permanent tissue damage in the case of chronic periodontitis. There are currently no experimental tissue models able to mimic the structural, physical, and metabolic conditions present in the human oral gingival tissue to support the long-term investigation of host-pathogens imbalances. Herein, the authors report an in vitro 3D anatomical gingival tissue model, fabricated from silk biopolymer by casting a replica mold of an adult human mandibular gingiva to recreate a tooth-gum unit. The model is based on human primary cultures that recapitulate physiological tissue organization, as well as a native oxygen gradient within the gingival pocket to support human subgingival plaque microbiome with a physiologically relevant level of microbial diversity up to 24 h. The modulation of inflammatory markers in the presence of oral microbiome indicates the humanized functional response of this model and establishes a new set of tools to investigate host-pathogen imbalances in gingivitis and periodontal diseases.

Aspects of oral streptococcal metabolic diversity: Imagining the landscape beneath the fog

“…These have involved the use of hydroxyapatite disks in saliva (Ito et al, 2017; Li et al, 2021; Shaddox et al, 2010; Walker & Sedlacek, 2007) and reconstructed human gingiva (RHG) (Buskermolen et al, 2016; Shang et al, 2019). Recently, a 3D reconstructed gingival tissue model was assembled on a silk/collagen substratum to recreate a tooth‐gum environment for the study of periodontal biofilm communities (Adelfio et al, 2023). The system was reported to recapitulate the oxygen gradients and human subgingival plaque microbial community residing within the human gingiva.…”

Sustaining healthy long-term host-microbiome interactions in a physiologically relevant dynamic gingival tissue model

“…The main setbacks are due to the complexity of recapitulating in vitro the oral host-pathogen niche features (i.e., oxygen and pH gradients) and microenvironmental stimuli (i.e., salivary flow, drinking, chewing) that ultimately dictates the continuously evolving relationship between the host and microbial populations to allow mutual coexistence within the oral environment 1,10 . Despite the recent research efforts 6,11,12 , a physiologically relevant model, encompassing all of these features, is still representing an unmet challenge in the field of oral tissue modeling.…”

“…Given the coevolution of the microbiome with the host and their organization in multiple habitats within the depth of the gingiva 1,5 , their interactions are challenging to study in both clinical and in vitro applications 6 . Pre-clinical and clinical studies are limited in investigating disease trajectories, while animal models show differences in microbiome compositions, organization, and disease initiation.…”

“…Pre-clinical and clinical studies are limited in investigating disease trajectories, while animal models show differences in microbiome compositions, organization, and disease initiation. Current therapies for periodontal conditions remain inadequate 7 and they are extremely costly due to routine care 6,8,9 . Yet, the application of in vitro research strategies using traditional tissue engineering strategies ( i.e., cells grown in tissue culture plastic or three-dimensional planar and static models) are still lacking several of the native human tissue nuances.…”

“…We have previously developed a three-dimensional humanized gingival tissue model based on natural proteins to recreate the anatomical architecture of an adult human lower-jaw gingiva. We have found that the ability to replicate the anatomical tissue architecture is crucial for the establishment of the physiological oxygen gradients within the periodontal pocket to support the long-term culture of microbial populations 6 . The model sustained interactions between human primary gingival cells and patient-derived subgingival plaque-derived microbiomes for up to 24 hours, while preserving microbiome richness and diversity.…”