The Era of Biomaterials: Smart Implants?

Conditions, accidents, and aging processes have brought with them the need to develop implants with higher technology that allow not only the replacement of missing tissue but also the formation of tissue and the recovery of its function. The development of implants is due to advances in different areas such as molecular-biochemistry (which allows the understanding of the molecular/cellular processes during tissue repair), materials engineering, tissue regeneration (which has contributed advances in the knowledge of the properties of the materials used for their manufacture), and the so-called intelligent biomaterials (which promote tissue regeneration through inductive effects of cell signaling in response to stimuli from the microenvironment to generate adhesion, migration, and cell differentiation processes). The implants currently used are combinations of biopolymers with properties that allow the formation of scaffolds with the capacity to mimic the characteristics of the tissue to be repaired. This review describes the advances of intelligent biomaterials in implants applied in different dental and orthopedic problems; by means of these advances, it is expected to overcome limitations such as additional surgeries, rejections and infections in implants, implant duration, pain mitigation, and mainly, tissue regeneration.

Antioxidant activity of kafirin hydrolysates on UVB irradiated human keratinocyte cells and in silico identification.

BACKGROUND: Ultraviolet B (UVB) causes photoaging of the skin, the appearance of wrinkles, spots, and alteration of the skin barrier. The main cells in the most superficial layer of the skin are the keratinocytes; these cells play an important role in protecting this organ. OBJECTIVE: The present study aimed to investigate the antioxidant activity of the hydrolysates from kafirin to inhibit UVB-induced responses in human keratinocytes cells (HaCaT). METHODS: Kafirin hydrolysates were produced by enzymatic hydrolysis with alcalase. The activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in the HaCaT cell line in the presence of UVB and the effects of the hydrolysates against the UVB-induced response were evaluated. Furthermore, the peptides that were generated by hydrolysis were identified in silico using the BIOPEP database. RESULTS: Two protein sequences were identified (α-kafirin and the precursor protein of α-kafirin), in the kafirin extract. A degree of hydrolysis of 18.8% was obtained by hydrolyzing the kafirin extract with alcalase. The kafirin hydrolysates avoided the decrease in endogenous antioxidant enzymes such as SOD, CAT, and GPx reducing the oxidative stress generated by UVB. Using the BIOPEP-UWM database, we found 102 peptide sequences, and it has shown that the peptides have a large amount of hydrophobic amino acids such as proline, alanine, and glutamine, and amino acids with high antioxidant capacity. CONCLUSION: These results suggest that the kafirin hydrolysates can be used as antioxidant agents to ameliorate UVB-induced skin keratinocytes cells' response in vitro, providing an alternative against UVB-induced photoaging.

Atrazine modifies markers of melanocyte maturation and apoptosis in primary skin cultures.

Atrazine (ATZ) is part of a group of herbicides called triazines. ATZ is widely used in agricultural areas of Mexico, commonly used for the selective control of weeds in corn and sorghum crops. The exposure to ATZ can have serious human health effects since its use was associated with the development of cutaneous melanoma in an epidemiological study. The aim of this study was to evaluate the expression of maturation and apoptotic markers in primary skin cultures exposed to ATZ. The primary skin cultures were exposed to 0.1, and 10 µM ATZ with or without ultraviolet (UV) radiation and the expression of maturation and apoptotic markers were evaluated by RT-qPCR. We observed a significant increase in all the melanocyte maturation markers in cells exposed to ATZ with or without UV, with SOX-9 and FAK (melanoblast markers) being the highest. Also, the expression of BCL-2 (anti-apoptotic marker) was the most increased gene in cells exposed to ATZ with or without UV. Low concentrations of ATZ and UV radiation induce genetic changes associated with the development of immature melanocytes and activate mechanisms associated with the inhibition of apoptosis characteristics of malignant cell transformation, which will allow proposing new therapeutic targets and generating new restrictions or care in farmers exposed to pesticides such as the ATZ.

In vitro effect of high glucose concentrations on erythrocyte morphology assessed by scanning electron microscopy.

AIMS: To evaluate the in vitro effect of different glucose concentrations and the time series in erythrocyte cell viability and morphology parameters. METHODS: Different glucose concentrations were assessed, from a normal physiological glucose concentration (5 mM) to a diabetes scenario (100 mM). Cell viability was obtained by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The erythrocyte morphology (diameter, height, and axial ratio) was assessed by scanning electron microscopy (SEM). RESULTS: A significant decrease in cell viability was observed in erythrocytes with higher glucose concentration (100 mM). There was also a significant increase in the cells' diameter and height exposed to 100 mM, vs. those cultured with 5, 20, and 45 mM glucose, but only at 24 and 48 h. When comparing the same glucose concentration by a time series, it was observed that erythrocytes from the culture with 45 and 100 mM of glucose had a significant continuous decrease (approximately -0.40 µm) in diameter and height (24, 48, and 72 h), but there was no difference in the axial ratio observed. CONCLUSION: Continuous exposure to high glucose concentrations in diabetes models produced less cell viability and changes in erythrocyte morphology (larger and scrambled cells), which in vivo might impact in microvascular complications.

Cytokines secretion from human mesenchymal stem cells induced by bovine bone matrix.

BACKGROUND: Bovine bone matrix is a natural material that has been used in the treatment of bone lesions. In this study, bovine bone matrix Nukbone® (NKB) was investigated due its osteoconductive and osteoinductive properties. This biomaterial induces CBFA-1 activation and osteogenic differentiation, although the cytokines involved in these processes is still unknown. OBJECTIVE: The aim of this work was to determine the influence of NKB on the pro-osteoblastic and anti-osteoblastic cytokines secretion from human mesenchymal stem cells (hMSCs). METHODS: The hMSCs were cultured onto NKB and cytokines IL-2, IL-4, IL-6, IL-10, IL-12, IFN-γ and TNF-α were analized at 0-14 days by immunoassay. In addition, hemocompatibility of NKB and characterization of hMSCs were evaluated. RESULTS: NKB induces an increase on pro-osteoblastic cytokine secretion IL-4 and a decrease on anti-osteoblastic cytokine IL-6 secretion, at days 7 and 14 of cell culture. Interestingly, there was no statistical difference between secretion profiles of others cytokines analized. CONCLUSIONS: The up-regulation of IL-4 and down-regulation of IL-6, and the secretion profiles of other cytokines examined in this work, are findings that will contribute to the understanding of the role of NKB, and similar biomaterials, in bone homeostasis and in the osteoblastic differentiation of hMSCs.

Optimization of Sorghum Kafirin Extraction Conditions and Identification of Potential Bioactive Peptides.

The interest in extracting kafirins (KAF), the main storage protein from sorghum grain has recently increased due to its gluten-free content and the significant scientific evidence showing the health benefits of the bioactive peptides from cereal grains in human diets. The objectives were to obtain the highest percentage of KAF extraction using amyloglucosidase as pretreatment to increase the extraction yield and predict the bioactive peptides in the KAF. In this study, pretreatments with amyloglucosidase increased the extraction yield of KAF compared with extraction methods using only ethanol and sodium metabisulfite. Two protein fragment sequences were identified from KAF extract and were evaluated for potential bioactive peptide using the BIOPEP-UWM database, which suggest that KAF proteins from white sorghum may be considered as good precursors of dipeptidyl peptidase-inhibitor, angiotensin-converting enzyme inhibitor, antioxidant and hypotensive peptides following chymotrypsin, thermolysin, and subtilisin and their combination. Average scores aligned using PeptideRanker confirmed KAF proteins' potential sources of bioactive peptides with over 5 peptides scored over 0.8. In addition, 31 unexplored peptide sequences that could have biological activity were identified. Our results suggest that KAF can be used in the peptide productions with potential biological activity and beyond.

Histopathological Diagnosis of Cervical Biopsies: Reduction of Sampling Errors with the Evaluation of a Third Histologic Level.

AIM: Cervical cancer (CC) is considered as a major public health problem; this disease affects mainly vulnerable women in poverty, causing a negative effect on a country's workforce. OBJECTIVE: To determine the histopathological diagnosis variation after examining three more levels of cervical biopsy paraffin blocks from patients with HPVI, CIN and CC. MATERIALS AND METHODS: A quantitative, retrospective correlational study was performed in a hospital with a second level of health care. We worked with 152 paraffin blocks of CIN (CIN, I, II and III) and cervical cancer samples. Currently, CIN I is considered as a set of low-grade injuries (low-grade squamous intraepithelial lesions, LSIL), while CIN II, CIN III and cancer in situ are considered as high-grade lesions (high-grade squamous intraepithelial lesions, HSIL). A slab was prepared with the 50micron block, which was subsequently cut into 5 microns; later, the same thing was done at two more levels to reevaluate the histopathological diagnosis and correlate it with the initial diagnosis issued by the institution. RESULTS: During the examination of the additional block levels, a difference was observed from the initial diagnosis: of 32 cases of HPV diagnosis, there were 17 changes to CIN I; of 31 cases of CIN I, there were 4 changes to CIN II; of 30 cases of CIN II, there were 8 changes to CIN III and 1 change to invasive cancer; of 29 cases of CIN III, there were 9 changes to cancer in situ; and finally, of 14 cases of cancer in situ, there was 1 change to invasive cancer. After the statistical analysis, a value of p <0.05 was obtained, which indicated that the differences were statistically significant. CONCLUSION: By modifying the histopathological study technique, guidelines can be given to generate a more accurate diagnosis with a more solid base, and thus, a more appropriate and timely treatment can be offered to avoid the development of cervical cancer.

Cell-free scaffold from jellyfish Cassiopea andromeda (Cnidaria; Scyphozoa) for skin tissue engineering.

Disruption of the continuous cutaneous membrane in the integumentary system is considered a health problem of high cost for any nation. Several attempts have been made for developing skin substitutes in order to restore injured tissue including autologous implants and the use of scaffolds based on synthetic and natural materials. Current biomaterials used for skin tissue repair include several scaffold matrices types, synthetic or natural, absorbable, degradable or non-degradable polymers, porous or dense scaffolds, and cells capsulated in hydrogels or spheroids systems so forth. These materials have advantages and disadvantages and its use will depend on the desired application. Recently, marine organisms such as jellyfish have attracted renewed interest, because both its composition and structure resemble the architecture of human dermic tissue. In this context, the present study aims to generate scaffolds from Cassiopea andromeda (C. andromeda), with application in skin tissue engineering, using a decellularization process. The obtained scaffold was studied by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry analysis (DSC), and scanning electron microscopy (SEM). Crystal violet staining and DNA quantification assessed decellularization effectiveness while the biocompatibility of scaffold was determined with human dermic fibroblasts. Results indicated that the decellularization process reduce native cell population leading to 70% reduction in DNA content. In addition, SEM showed that the macro and microstructure of the collagen I-based scaffold were preserved allowing good adhesion and proliferation of human dermic fibroblasts. The C. andromeda scaffold mimics human skin and therefore represents great potential for skin tissue engineering.

Isolation of human mesenchymal stem cells and their cultivation on the porous bone matrix.

Mesenchymal stem cells (MSCs) have a differentiation potential towards osteoblastic lineage when they are stimulated with soluble factors or specific biomaterials. This work presents a novel option for the delivery of MSCs from human amniotic membrane (AM-hMSCs) that employs bovine bone matrix Nukbone (NKB) as a scaffold. Thus, the application of MSCs in repair and tissue regeneration processes depends principally on the efficient implementation of the techniques for placing these cells in a host tissue. For this reason, the design of biomaterials and cellular scaffolds has gained importance in recent years because the topographical characteristics of the selected scaffold must ensure adhesion, proliferation and differentiation into the desired cell lineage in the microenvironment of the injured tissue. This option for the delivery of MSCs from human amniotic membrane (AM-hMSCs) employs bovine bone matrix as a cellular scaffold and is an efficient culture technique because the cells respond to the topographic characteristics of the bovine bone matrix Nukbone (NKB), i.e., spreading on the surface, macroporous covering and colonizing the depth of the biomaterial, after the cell isolation process. We present the procedure for isolating and culturing MSCs on a bovine matrix.

Nukbone® promotes proliferation and osteoblastic differentiation of mesenchymal stem cells from human amniotic membrane.

Bovine bone matrix Nukbone® (NKB) is an osseous tissue-engineering biomaterial that retains its mineral and organic phases and its natural bone topography and has been used as a xenoimplant for bone regeneration in clinics. There are not studies regarding its influence of the NKB in the behavior of cells during the repairing processes. The aim of this research is to demonstrate that NKB has an osteoinductive effect in human mesenchymal stem cells from amniotic membrane (AM-hMSCs). Results indicated that NKB favors the AM-hMSCs adhesion and proliferation up to 7 days in culture as shown by the scanning electron microscopy and proliferation measures using an alamarBlue assay. Furthermore, as demonstrated by reverse transcriptase polymerase chain reaction, it was detected that two gene expression markers of osteoblastic differentiation: the core binding factor and osteocalcin were higher for AM-hMSCs co-cultured with NKB in comparison with cultivated cells in absence of the biomaterial. As the results indicate, NKB possess the capability for inducing successfully the osteoblastic differentiation of AM-hMSC, so that, NKB is an excellent xenoimplant option for repairing bone tissue defects.