METHOD: A strain comprising 10% direct compression and 1% compressive shear was applied to bovine chondrocytes seeded in an agarose gel during two 12-hour conditioning periods separated by a 12-hour resting period.
RESULTS: The bi-axial-loaded chondrocytes demonstrated a significant increase in glycosaminoglycan synthesis compared with samples exposed to uni-axial or no loading over the same period (p<0.05). The use of a free-swelling recovery period prior to the loading regime resulted in additional glycosaminoglycan production and a significant increase in DNA content (p<0.05), indicating cell proliferation.
CONCLUSIONS: These results demonstrate that the use of a bi-axial loading regime results in increased matrix production compared with uni-axial loading.
RECENT FINDINGS: Advance in the imaging study provides more accurate assessment of fMMC in utero. Prenatal maternal--fetal surgery in fMMC demonstrates favourable postnatal outcome. Minimally invasive fetal surgery minimizes uterine wall disruption. Endoscopic fetal surgery is performed via laparotomy-assisted or entirely percutaneous approach. The postnatal outcome for open and endoscopic fetal surgery shares no difference. Single layer closure during repair of fMMC is preferred to reduce postnatal surgical intervention. All maternal--fetal surgeries impose anesthetic and obstetric risk to pregnant woman. Ruptured of membrane and preterm delivery are common complications. Trans-amniotic stem cell therapy (TRASCET) showed potential tissue regeneration in animal models. Fetal tissue engineering with growth factors and dura substitutes with biosynthetic materials promote spinal cord regeneration. This will overcome the challenge of closure in large fMMC. Planning of the maternal--fetal surgery should adhere to ethical framework to minimize morbidity to both fetus and mother.
SUMMARY: Combination of endoscopic fetal surgery with TRASCET or tissue engineering will be a new vision to achieve to improve the outcome of prenatal intervention in fMMC.
RECENT FINDINGS: Recent advances in hydrogel-based engineering of vascularized organ bud enable vascular regeneration in self-assembled cellular niche containing parenchymal and stromal cells. The emerging technology of whole-organ decellularization provides scaffold materials that serve as extracellular niche guiding vascular regeneration to recapitulate native organ's vascular anatomy. Increasing morphological and molecular evidences suggest endothelial heterogeneity across different organs and across different vascular compartments within an organ. Deriving organ-specific endothelium from pluripotent stem cells has been shown to be possible by combining endothelial induction with parenchymal differentiation.
SUMMARY: Engineering organ-specific vasculature requires the combination of organ-specific endothelium with its unique cellular and extracellular niches. Future investigations are required to further delineate the mechanisms for induction and maintenance of organ-specific vascular phenotypes, and how to incorporate these mechanisms to engineering organ-specific vasculature.
METHODS: Review of the literature was conducted using keywords (and MeSH) like Bioreactor, Regenerative Dentistry, Fourth Factor, Stem Cells, etc., from the journals published in English. All the searched abstracts, published in indexed journals were read and reviewed to further refine the list of included articles. Based on the relevance of abstracts pertaining to the manuscript, full-text articles were assessed.
RESULTS: Bioreactors provide a prerequisite platform to create, test, and validate the biomaterials and techniques proposed for dental tissue regeneration. Flow perfusion, rotational, spinner-flask, strain and customize-combined bioreactors have been applied for the regeneration of bone, periodontal ligament, gingiva, cementum, oral mucosa, temporomandibular joint and vascular tissues. Customized bioreactors can support cellular/biofilm growth as well as apply cyclic loading. Center of disease control & dip-flow biofilm-reactors and micro-bioreactor have been used to evaluate the biological properties of dental biomaterials, their performance assessment and interaction with biofilms. Few case reports have also applied the concept of in vivo bioreactor for the repair of musculoskeletal defects and used customdesigned bioreactor (Aastrom) to repair the defects of cleft-palate.
CONCLUSIONS: Bioreactors provide a sterile simulated environment to support cellular differentiation for oro-dental regenerative applications. Also, bioreactors like, customized bioreactors for cyclic loading, biofilm reactors (CDC & drip-flow), and micro-bioreactor, can assess biological responses of dental biomaterials by simultaneously supporting cellular or biofilm growth and application of cyclic stresses.
AIM: Thus, this review is focused on understanding their potential uses and factors influencing their pluripotent status in vitro.
CONCLUSION: In short, this cell source could be an ideal cellular resource for pluripotent cells for potential applications in allogeneic cellular replacement therapies, fetal tissue engineering, pharmaceutical screening, and in disease modelling.