Ph.D. Defense: Priyanka Ruparelia, Nanoscience

Ph.D. Defense: Priyanka Ruparelia, Nanoscience

February 28th, 2019 at 9 am in the JSNN auditorium

SYNTHESIS AND CHARACTERIZATION OF BACTERIAL CELLULOSE TOWARDS

OSTEOGENIC DIFFERENTIATION OF STEM CELLS

Priyanka Ruparelia, Nanoscience

The extracellular matrix provides physical support and functional microenvironment in which cells exist for healthy tissue formation and maintenance. This dynamic interplay between the extracellular matrix and cells have significant effect on cellular functions like cell adhesion, cell proliferation and cell differentiation. To mimic this multimolecular three-dimension network during tissue damage, like disease, trauma or functional failure, tissue engineering introduces us to apply the principles of material science and life science for developing biocompatible materials.

According to 2019 United Network for Organ Sharing report 3,180 transplants were performed with 113,839 people still on the waiting list. The sole reliance on transplantation has not only created a waiting list but also a rise in the health care cost. Current strategies involve the use of donated organs or tissues either from one patient to another or from one part of the patient’s body to another part of the body in the same patient. These practices have limitations like immunogenic rejection, risk of disease transmission, costly immunosuppression therapies and difficult and time-consuming surgical procedures. Therefore, there is a growing need for modifying factors like biomaterials that act as scaffold matrices and serve as a platform for the cells to grow and form tissues upon transplantation. In this study, we have utilized a biomimetic approach to produce a material that acts as a bioscaffold while examining its properties for its application in the field of bone tissue engineering.

Bacterial cellulose is a polysaccharide material that is synthesized by specific types of bacteria like Acetobacter, Azotobacter, Gluconacetobacter, Pseudomonas, Salmonella and Sarcina ventriculi. Among them the most effective are Gluconacetobacter xylinum, Gluconacetobacter hansenii, and Gluconacetobacter pasteurianus. These bacteria polymerize glucose residues into linear β-1,4-glucan chains that assemble and crystallize cellulose ribbons. These ribbons form a three-dimensional network of cellulose nanofibers with ideal properties like hydrophilicity, high surface area, excellent mechanical property, moldability and high purity as compared to plant cellulose. In this work, we have fermented bacterial cellulose using Gluconacetobacter Hansenii that produces a pellicle of cellulose with similar properties. Human-derived placental mesenchymal stem cells were cultured on bacterial cellulose to study its osteogenic differentiation potential to function as a cell-scaffold construct for bone regeneration.

Our study found novel advances that enable bacterial cellulose to support the growth and differentiation of human-derived placental mesenchymal stem cell in vitro. Material characterization showed that bacterial cellulose has a fiber diameter of 40-60nm with twisted and interwoven cellulose fibrils caused due to the rotation of bacteria during fermentation. In its never-dried state the material is flexible and has a high stiffness while being brittle upon drying. The nanoscale feature of bacterial cellulose supported the growth of placental stem cells and showed no toxicity upon culturing for long hours. Further, the hydrophilic nature of bacterial cellulose enabled the differentiation of placental stem cells with high expression of early osteogenic marker like alkaline phosphatase and an increase in mineralized matrix by the end of 28 days. We have established the importance of hydrophilicity, nanotopography and material structure that showed improved biomineralization during osteogenic differentiation. This study provides a strong basis that material properties play a vital role in supporting the growth of the cells and its ability to deposit tissue-specific extracellular matrix. In this study, Bacterial cellulose showed as a promising biomaterial for bone tissue engineering applications

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