Self-Assembly of an Organized Cementum-Periodontal Ligament-Like Complex Using Scaffold-Free Tissue Engineering

Abstract

A major challenge in regenerating periodontal tissues is emulating its complex structure containing both mineralized and soft tissues. In this study, scaffold-free tissue constructs engineered using periodontal ligament cells (PDLCs), which contain a population of adult stem/progenitor cells, self-assembled into an organized multi-tissue structure comprising a mineralized cementum-like core enclosed within a periodontal ligament (PDL)-like tissue. Scaffold-free engineered constructs were formed by culturing human PDLCs to form a cell sheet on six-well dishes containing two minutien pins placed 7 mm apart. The cell sheet was contracted by the cells to roll into the pins forming a cylindrical construct anchored on either end by the pins. These tissues were approximately 1 mm in diameter and 7 mm long and contained only the cells and their endogenous matrix. These scaffold-free engineered constructs exhibited two structurally distinct tissues, one in the center of the construct and another on the periphery. The center tissue was mineralized and expressed alkaline phosphatase and bone sialoprotein, similar to cementum. The peripheral tissue was not calcified and expressed periodontal ligament-associated protein-1 and periostin, which is characteristic of the periodontal ligament. This tissue organization was seen after in vitro culture and maintained in vivo following subcutaneous implantation in immunocompromised mice. These data demonstrate that scaffold-free tissue engineering facilitates PDLCs to self-assemble into an organized cementum-PDL-like complex. These engineered tissues could be used as implantable grafts to regenerate damaged periodontal tissues or as model systems to study PDLC biology and mechanisms driving organized tissue assembly within the periodontium.

Low‐intensity pulsed ultrasound promotes the formation of periodontal ligament stem cell sheets and ectopic periodontal tissue regeneration

“…The cell‐sheets can completely maintain the ECM protein between cells and form a three‐dimensional structure without any scaffold material, thereby increasing post‐implantation survival 17,18 . Tsumanuma et al observed the newly formed cementum and well‐aligned fibrous structure after implanting PDL cell (PDLC) sheets and β‐tricalcium phosphate complex into the canine wall defect for 8 weeks, 19 and Basu et al demonstrated that implantation of PDLC sheets into immunocompromised mice can form a cementum‐periodontium‐like composite structure 20 . These findings indicate that the PDLC sheets have great potential for the application of periodontal tissue engineering.…”

Current Trends in In Vitro Modeling to Mimic Cellular Crosstalk in Periodontal Tissue

“…[103] In fact, this scaffold-free tissue engineering method favors PDLderived cells self-assembling in a structure that mirrors the complexity of periodontium. [104] More importantly, organized cell structures are maintained in vivo where they express key molecules required for PDL remodeling. These structures are also suitable for a co-culture of additional cell types.…”

Fabrication and characterization of mechanically competent 3D printed polycaprolactone-reduced graphene oxide scaffolds

“…A myriad of techniques are available to fabricate scaffolds including solvent casting 5 , freeze casting 6 , freeze drying 7 , electrospinning 8 , gas foaming 9 , particulate-leaching 10 , melt molding 11 , phase separation 12 , and self-assembly 13 and sol–gel methods 14 . However, most techniques are limited by their poor control over scaffold design, architecture, pore network and pore size.…”