ABSTRACT
Tissue engineering aims to develop in-vitro substitutes of native tissues. One approach of tissue engineering relies on using bioreactors combined with biomimetic scaffolds to produce study models or in-vitro substitutes. Bioreactors provide control over environmental parameters, place and hold a scaffold under desired characteristics, and apply mechanical stimulation to scaffolds. Polymers are often used for fabricating tissue-engineering scaffolds. In this study, polycaprolactone (PCL) collagen-coated microfilament scaffolds were cell-seeded with C2C12 myoblasts; then, these were grown inside a custom-built bioreactor. Cell attachment and proliferation on the scaffolds were investigated. A loading pattern was used for mechanical stimulation of the cell-seeded scaffolds. Results showed that the microfilaments provided a suitable scaffold for myoblast anchorage and that the custom-built bioreactor provided a qualified environment for the survival of the myoblasts on the polymeric scaffold. This PCL-based microfilament scaffold located inside the bioreactor proved to be a promising structure for the study of skeletal muscle models and can be used for mechanical stimulation studies in tissue engineering applications.
ABSTRACT
An appropriate and reliable sterilization technique is crucial for tissue engineering scaffolds. Skeletal muscle scaffolds are often fabricated using microfilaments of a wide variety of polymers. One method for sterilization is 25 kGy of gamma irradiation. In addition, sterilization through irradiation should administer a dose within a specific range. Radiation directly affects the chemical and mechanical properties of scaffolds. The accuracy and effects of irradiation are often not considered during sterilization procedures; however, these are important since they provide insight on whether the sterilization procedure is reliable and reproducible. This study focused on the chemical and mechanical characterization of 25 kGy gamma-irradiated scaffold. The accuracy and uncertainty of the irradiation procedure were also obtained. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were performed to determine whether the crystallinity of the polymer changed after irradiation and whether gamma rays influenced its thermal properties. The tensile parameters of the microfilaments were analyzed by comparing irradiated and nonirradiated scaffolds to determine whether gamma radiation changed their elastic behavior. Dose distribution and uncertainty were recorded with several dosimeters. The results showed that the irradiation process slightly affected the mechanical parameters of the scaffold; however, it did not modify its crystallinity or thermal properties. The irradiation was uniform, since the measured uncertainty was low. The scaffold was pathogen-free after 7 days; this meant sterilization was achieved. These results indicated that gamma-sterilized scaffolds were a promising material for use as a skeletal muscle analog material for tissue-engineering applications because they can be sterilized with gamma rays without changing their chemical structure and mechanical properties. This study provided the dose distribution measurement and uncertainty calculations for the sterilization procedure.
ABSTRACT
Resumen El plasma rico en plaquetas es un producto derivado de la sangre, rico en péptidos y proteínas de señalización intercelular, así como citoquinas capaces de intervenir en cada una de las etapas de la regeneración de varios tejidos. Principalmente, se le han atribuido efectos antiinflamatorios en diferentes lesiones, así como otros efectos biológicos sobre las células y tejidos. A la fecha, no existe un protocolo estándar de producción o preparación, tampoco se ha descrito una dosis específica; la forma de aplicación es muy variable y depende de la condición por tratar. A pesar de ello, se han visto efectos positivos en campos como: odontología, ortopedia, dermatología, medicina reconstructiva, oftalmología, medicina deportiva, medicina vascular, entre otros. Su regulación es muy diversa a nivel internacional. Aunque hay expectativas con el tratamiento de plasma rico en plaquetas, no hay suficientes ensayos clínicos robustos que brinden un alto nivel de evidencia para validarlo como un tratamiento de rutina frente a determinada condición clínica. Además, no se pueden comparar fácilmente los resultados de diferentes investigaciones, por la variabilidad en el método de preparación y por la falta de homogeneidad en las lesiones tratadas, entre otros factores. Es por lo anterior que resulta necesario desarrollar más investigaciones serias que conlleven al establecimiento de un protocolo estandarizado, así como demostrar la efectividad de este nuevo tratamiento, de forma que se culmine con la implementación de nuevas terapias validadas y autorizadas para garantizar una mejoría real a los pacientes.
Abstract Platelet-rich plasma is a blood-derived product, rich in peptides and intercellular signaling proteins and cytokines capable of intervening in each stage of the regeneration of various tissues. Mainly, it has been attributed anti-inflammatory effects in different lesions, as well as other biological effects on cells and tissues. To date, there is no standard production or preparation protocol, nor has a specific dose been described. The form of application is very variable and depends on the condition to be treated. Despite this, positive effects have been seen in different fields such as: dentistry, orthopedics, dermatology, reconstructive medicine, ophthalmology, sports medicine, vascular medicine among others. Its regulation is very diverse internationally. Although there is a lot of expectation with the treatment of platelet-rich plasma, there are not enough robust clinical trials that provide a high level of evidence to validate it as a routine treatment for a certain clinical condition. In addition, the results of different investigations cannot be easily compared due to the variability in the method of preparation and the lack of homogeneity in the treated lesions, among other factors. It is for this reason that it is necessary to develop more serious investigations that lead to the establishment of a standardized protocol, as well as to demonstrate the effectiveness of this new treatment and culminate with the implementation of new validated and authorized therapies to guarantee a real improvement to the patients.
Subject(s)
Humans , Costa Rica , Blood-Derivative Drugs , Platelet-Rich Plasma , Platelet-Rich Plasma/chemistryABSTRACT
Resumen Objetivo: se diseñó un estudio que evaluara la tasa de cicatrización cutánea en úlceras agudas en ratas Sprague-Dawley después de recibir la administración de células madre mesenquimatosas derivadas de tejido adiposo. Métodos: al primer grupo, denominado células madre (CM), se le administró células mesenquimatosas derivadas de tejido adiposo inyectadas, tanto periulcerosa como intraulcerosa. El segundo grupo, denominado neobol (N), recibió tratamiento con neobolR tópico, cuyo principio activo es el clostebol. El tercer grupo, denominado control (C), fue sometido a la misma manipulación quirúrgica que los dos grupos anteriores, pero no recibió ningún tipo de tratamiento. Después de realizar una úlcera aguda en el dorso de las ratas y recibir el tratamiento respectivo, se evaluó la tasa de cicatrización (día 1 de la úlcera - día X úlcera) / día 1 de la úlcera en todos los grupos. Resultados: se extrajo un promedio de 1,22 ± 0,46 g de muestra y se aislaron 3,5 x 105 células, con un inóculo promedio de 2,4 x 104 y una viabilidad del 95,5%. La positividad para el antígeno CD29 mediante citometría de flujo fue del 96,5%. El análisis histológico realizado a los 7 días posteriores a la cicatrización clínica, demostró que el grupo de CM presentó la combinación de mayor vascularización y formación de epitelio, así como mayor porcentaje de cicatrización en relación con el grupo N (H(1)=5,61; p < 0,01) y C (H(1)=10,47; p < 0,001). Conclusión: el estudio sugiere que las células madre derivadas del tejido adiposo aumentan la tasa de cicatrización.
Abstract Objective: To evaluate the rate of cutaneous cicatrization of acute ulcers in Sprague-Dawley rats, after receiving the administration of mesenchymal stem cells derived from adipose tissue. Methods: There were three experimental groups. After an acute ulcer was performed in the backs of the rats they received either stem cells (SC), Clostebol, (NeobolR group, N) or no treatment (control group, C), the ulcer cutaneous healing rate was assessed as follows: (ulcer day 1 - ulcer day X)/in all groups day 1. Stem cells were extracted from adipose tissue in the inguinal pad and then injected in the Stem cells group. Results: An average of 1.22 ± 0,46 grams (g) of adipose tissue was extracted and 3.5 x 105 cells were isolated with an average 2.4 x 104 inoculant, 95,5% cell viability. The CD29 antigen positivity on the stem cells assessed by flow cytometry was 96,5%. The histological analysis performed 7 days after the clinical healing showed that the SC group showed the highest vascularization and epithelial tissue formation. When comparing the average healing percentage among groups, only the SC group showed significant differences in contrast with the N group (H (1) = 5.61; p < 0,01) and C (H (1) = 10.47; p< 0.001). Conclusion: This study suggests that mesenchymal cells derived from adipose tissue increase the healing rate.
