Loreto M. Valenzuela

Improving myoblast differentiation on electrospun poly(ε‐caprolactone) scaffolds

Polymer scaffolds are used as an alternative to support tissue regeneration when it does not occur on its own. Cell response on polymer scaffolds is determined by factors such as polymer composition, topology, and the presence of other molecules. We evaluated the cellular response of murine skeletal muscle myoblasts on aligned or unaligned fibers obtained by electrospinning poly(ε-caprolactone) (PCL), and blends with poly(lactic-co-glycolic acid) (PLGA) or decorin, a proteoglycan known to regulate myogenesis. The results showed that aligned PCL fibers with higher content of PLGA promote cell growth and improve the quality of differentiation with PLGA scaffolds having the highest confluence at over 68% of coverage per field of view for myoblasts and more than 7% of coverage for myotubes. At the same time, the addition of decorin greatly improves the quantity and quality of differentiated cells in terms of cell fusion, myotube length and thickness, being 71, 10, and 51% greater than without the protein, respectively. Interestingly, our results suggest that at certain concentrations, the effect of decorin on myoblast differentiation exceeds the topological effect of fiber alignment.

Developing a Suitable Model for Water Uptake for Biodegradable Polymers Using Small Training Sets

Prediction of the dynamic properties of water uptake across polymer libraries can accelerate polymer selection for a specific application. We first built semiempirical models using Artificial Neural Networks and all water uptake data, as individual input. These models give very good correlations (R 2 > 0.78 for test set) but very low accuracy on cross-validation sets (less than 19% of experimental points within experimental error). Instead, using consolidated parameters like equilibrium water uptake a good model is obtained (R 2 = 0.78 for test set), with accurate predictions for 50% of tested polymers. The semiempirical model was applied to the 56-polymer library of L-tyrosine-derived polyarylates, identifying groups of polymers that are likely to satisfy design criteria for water uptake. This research demonstrates that a surrogate modeling effort can reduce the number of polymers that must be synthesized and characterized to identify an appropriate polymer that meets certain performance criteria.

Chitosan/poly‐octanoic acid 2‐thiophen‐3‐yl‐ethyl ester blends as a scaffold to maintain myoblasts regeneration potential in vitro

Satellite cells are a small cell population that function as muscle-specific adult stem cells. When muscle damage occurs, these cells are able to activate, proliferate, and ultimately fuse with each other in order to form new myofibers or fuse with existing ones. For tissue engineering applications, obtaining a sufficient number of myoblasts prior transplantation that maintains their regenerative capacity is critical. This can be obtained by in vitro expansion of autologous satellite cells. However, once plated, the self-renewal and regenerative capacity of myoblasts is rapidly lost, obtaining low yields per biopsy. For this purpose, we evaluated in vitro culture of the murine myoblast cell line C2C12 and mouse primary myoblasts with chitosan and chitosan/poly-octanoic acid 2-thiophen-3-yl-ethyl ester blends (poly(OTE)). The films of chitosan/poly(OTE) blends were heterogeneous and slightly rougher than chitosan and poly(OTE) films. Poly(OTE) presence improved myoblast adhesion in both cell types and prevented complete differentiation, but maintaining their differentiation potential in vitro. We identified that the polymer blend chitosan/poly(OTE) could be a suitable substrate to culture satellite cells/myoblasts in vitro preventing differentiation prior transplantation.

Relation between composition, antioxidant and antibacterial activities and botanical origin of multifloral bee pollen

Harvested bee pollen is valuable for its nutritional value and healthy properties. This work relates the botanical origin of sixteen bee pollens from Chile with their phenolic, protein and carotenoid content, and antioxidant/antibacterial activities. Our results showed that the chemical properties of different bee pollens are associated with the plant’ species from which each one was derived from. Some correlations between chemical properties and botanical origin were observed. Bee pollen showed between 20.0- 30.4% protein, 2.8-50.2 mg/kg carotenoids, 22.8-918.4 mg/kg phenolics, and 4.51-91.19 mmol Fe+2/kg pollen. Antibacterial activity was observed against all bacteria assayed even surpassing the activity of traditional antibiotics. Brassica sp. and Galega officinalis are an abundant source of antioxidants and antibacterial compounds. Other species such as those derived from fruit and endemic plants from Chile, although they occur less frequently, are also good source of these compounds. Some correlations between botanical origin and chemical, antioxidant and antibacterial properties were observed. Knowing the influence of plant species over the antioxidant and antibacterial properties of bee pollen, will allow selecting the best location for honeycombs and will allow beekeepers to differentiate and add value to their products.