In tissue engineering, bone scaffolds are at the vanguard of accelerating developments in tissue repair. In this study, electrospun scaffolds were used as the substrate to culture pre-osteoblastic murine calvaria cells MC3T3. Two compositions of electrospun scaffolds were investigated during this study. One scaffold was electrospun from a solution of poly-L-lactide (PLLA) and trace amounts of Type I collagen, and the other was composed only of PLLA. PLLA is a biocompatible and biodegradable polymer, making it an ideal candidate for tissue engineering -yet one limitation is its extremely hydrophobic nature. Therefore, the inclusion of collagen, a major extracellular matrix protein, was hypothesized to promote cell adhesion and proliferation on the scaffolds. We assayed 3 types of scaffolds (n=4): PLLA alone, PLLA with .52% collagen, and PLLA with 1.3% collagen. Nuclear fast red staining made observation of cell adhesion and morphology possible by staining the cytoplasm and nucleus different shades of pink. An MTS assay (CellTiter One Aqueous Solution) quantified cell proliferation through reagent permeation of the cell membrane and chemical interaction with cellular enzymes. The reagent then darkened the cellular media, quantifiable through ultraviolet spectroscopy. Scaffolds were analyzed at time points between days 1 and 14. Cell proliferation was observed on all scaffolds regardless of collagen concentration, even though it is known that the hydrophobic nature of PLLA hinders cell proliferation. Future studies will use a non-cytotoxic fluorescent marker so that cell growth on a single scaffold can be monitored over time, thus eliminating variability among the scaffolds. This will also enable us to study the interactions between the cells and scaffolds to find the optimal collagen concentration in PLLA. Another technique we used to incorporate collagen into the PLLA scaffold is dipping. In electrospinning, the exact interaction between collagen and polymer fiber in the scaffold is ambiguous, but dipping theoretically ensures that collagen will adhere to the surface of individual fibers. The scaffold was dipped into a 1 mg/ml solution of collagen in 0.1N acetic acid at time points 5, 10, 60, 180, and 240 minutes. After being dried in a vacuum-desiccator overnight, the scaffolds were seeded with MC3T3 cells. The longer the scaffold soaked in the solution, the higher probability that more collagen would be adsorbed onto the surface of the fibers comprising the scaffold. As observed through the staining intensity of the nuclear fast red staining, the affinity the cells have for the scaffold increased with the duration of the dipping. However, the MTS assay did not correlate with these results. In fact, the MTS assay indicated that longer dipping periods have no apparent effect on cell adhesion to the scaffold. To address this discrepancy, future work will use a non-cytotoxic fluorescent marker to trace the growth of cells on the scaffolds. A method will also be developed to quantify the amount of collagen actually on the scaffold as well as determining the dipping time for complete saturation of the scaffold. This study was funded by the Simons Summer Research Fellowship Program, Stonybrook Technology and Applied Research (STAR), and National Institute of Health (NIH).