Carla Cunha

Transplantation of nanostructured composite scaffolds results in the regeneration of chronically injured spinal cords

The destruction and hollowing of entire tissue segments represent an insurmountable barrier to axonal regeneration and therapeutics in chronic spinal cord injury. To circumvent this problem, we engineered neural prosthetics, by assembling electrospun nanofibers and self-assembling peptides into composite guidance channels and transplanted them into the cysts of a postcontusive, chronic spinal cord injury rat model, also providing delivery of proregenerative cytokines. Six months later conspicuous cord reconstruction was observed. The cyst was replaced by newly formed tissue comprising neural and stromal cells. Nerve fibers were interspersed between and inside the guidance channels, spanning the lesion, amidst a well-developed vascular network, basal lamina, and myelin. This was accompanied by a significant improvement in the activity of ascending and descending motor pathways and the global locomotion score. Thus by engineering nanostructured matrices into neuroprosthetics, it is possible to recreate an anatomical, structural, and histological framework, which leads to the replacement of large, hollow tissue gaps in the chronically injured spinal cord, fostering axonal regeneration and neurological recovery.

Osteochondral tissue engineering approaches for articular cartilage and subchondral bone regeneration

PurposeOsteochondral defects (i.e., defects which affect both the articular cartilage and underlying subchondral bone) are often associated with mechanical instability of the joint and therefore with the risk of inducing osteoarthritic degenerative changes. This review addresses the current surgical treatments and most promising tissue engineering approaches for articular cartilage and subchondral bone regeneration.MethodsThe capability to repair osteochondral or bone defects remains a challenging goal for surgeons and researchers. So far, most clinical approaches have been shown to have limited capacity to treat severe lesions. Current surgical repair strategies vary according to the nature and size of the lesion and the preference of the operating surgeon. Tissue engineering has emerged as a promising alternative strategy that essentially develops viable substitutes capable of repairing or regenerating the functions of damaged tissue.ResultsAn overview of novel and most promising osteochondroconductive scaffolds, osteochondroinductive signals, osteochondrogenic precursor cells, and scaffold fixation approaches are presented addressing advantages, drawbacks, and future prospectives for osteochondral regenerative medicine.ConclusionTissue engineering has emerged as an excellent approach for the repair and regeneration of damaged tissue, with the potential to circumvent all the limitations of autologous and allogeneic tissue repair.Level of evidenceSystematic review, Level III.

Brain-derived neurotrophic factor (BDNF) overexpression in the forebrain results in learning and memory impairments

In this study we analyzed the effect on behavior of a chronic exposure to brain-derived neurotrophic factor (BDNF), by analysing a mouse line overexpressing BDNF under the alphaCaMKII promoter, which drives the transgene expression exclusively to principal neurons of the forebrain. BDNF transgenic mice and their WT littermates were examined with a battery of behavioral tests, in order to evaluate motor coordination, learning, short and long-term memory formation. Our results demonstrate that chronic BDNF overexpression in the central nervous system (CNS) causes learning deficits and short-term memory impairments, both in spatial and instrumental learning tasks. This observation suggests that a widespread increase in BDNF in forebrain networks may result in adverse effects on learning and memory formation.

Predicting sampling saturation of mtDNA haplotypes: an application to an enlarged Portuguese database

An enlarged mtDNA database (n=549) for the Portuguese population, comprising HVRI and HVRII regions is reported. This database was used to test the effect of sample size on the estimation of relevant parameters such as haplotype diversity, number of different haplotypes, nucleotide diversity and number of polymorphic positions. Simulations were performed generating sets of random subsamples of variable sizes (n=50, 100, 200, 300 and 400). The results show that while haplotype and nucleotide diversities do not vary significantly with sample size, the numbers of haplotypes and polymorphic positions rise continuously inside the tested interval. These trends are interpretable by the evolution of the proportions of sequences that are found once or twice, which drop dramatically as sample size increases, with the corresponding rise in the frequency of those encountered 3 times or more. The generated data were also used to extrapolate saturation curves for the referred parameters. When considering for instance the number of haplotypes, it is shown that a sample size of 1,000 individuals is required for practical saturation (defined as the point where a sample size increase of 100 individuals corresponds to an increment in the diversity measure below 5%). For HVRII the same level is reached at n=900 and n=1,300 is needed when both regions are analysed simultaneously. Consequently, we can infer that currently used sample sizes are still rather inadequate for both anthropological and forensic purposes.

Inflammation in intervertebral disc degeneration and regeneration.

Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players.

Magnetic Bioinspired Hybrid Nanostructured Collagen–Hydroxyapatite Scaffolds Supporting Cell Proliferation and Tuning Regenerative Process

A bioinspired mineralization process was applied to develop biomimetic hybrid scaffolds made of (Fe(2+)/Fe(3+))-doped hydroxyapatite nanocrystals nucleated on self-assembling collagen fibers and endowed with super-paramagnetic properties, minimizing the formation of potentially cytotoxic magnetic phases such as magnetite or other iron oxide phases. Magnetic composites were prepared at different temperatures, and the effect of this parameter on the reaction yield in terms of mineralization degree, morphology, degradation, and magnetization was investigated. The influence of scaffold properties on cells was evaluated by seeding human osteoblast-like cells on magnetic and nonmagnetic materials, and differences in terms of viability, adhesion, and proliferation were studied. The synthesis temperature affects mainly the chemical-physical features of the mineral phase of the composites influencing the degradation, the microstructure, and the magnetization values of the entire scaffold and its biological performance. In vitro investigations indicated the biocompatibility of the materials and that the magnetization of the super-paramagnetic scaffolds, induced applying an external static magnetic field, improved cell proliferation in comparison to the nonmagnetic scaffold.

African Female Heritage in Iberia: A Reassessment of mtDNA Lineage Distribution in Present Times

The Iberian peninsula is a peripheral region of Europe in close proximity to Africa. Its inhabitants have an overall mtDNA genetic landscape typical of European background, although with signs of some African influence, whose features we deemed to disclose by analyzing available mtDNA HVRI distributions and new data. We analyzed 1,045 sequences. The most relevant results are the following: (1) North African sequences (haplogroup U6) present an overall frequency of 2.39%, and sub-Saharan sequences reach 3.83%, values that are, in both cases, much higher than those generally observed in Europe; and (2) there is a substantial geographic heterogeneity in the distribution of these lineages (haplogroup L being the most frequent in the south, whereas haplogroup U6 is generally more common in the north). The analysis of the observed diversity within each haplogroup strongly suggests that both were recently introduced (in historical times). Although for haplogroup U6 the documented event that is demographically compatible is the Islamic period (beginning of the 8th century to the end of the 15th century), for haplogroup L the most probable origin is the modern slave trade (mid 15th century to the end of the 18th century). However, the observed geographic structuring for one of the haplogroups does not fit the expected distribution provided by simplistic historical considerations. In fact, although for haplogroup L the north-south increasing frequency is corroborated by historical data, the opposite trend, observed for haplogroup U6, is more difficult to reconcile with the magnitude and time span of the Islamic political and cultural influence, which lasted longer and was more intense in the south. To clarify this conundrum, we need not only a substantial increase in the amount of mtDNA data (particularly for North Africa) but also new historical data and interpretations.

Therapist Interventions and Client Innovative Moments in Emotion-Focused Therapy for Depression

According to the narrative approach, change in self-narratives is an important part of successful psychotherapy. In this view, several authors have highlighted the usefulness of narrating new experiences (like actions, thoughts, and stories) during therapy in contrast with maladaptive client self-narratives. These new experiences are termed here innovative moments (IMs), and different types can be specified: action, reflection, protest, reconceptualization, and performing change. With the aim of understanding which therapist skills are related to client IMs, we analyzed the association between exploration, insight, and action skills and IMs in two initial, two middle, and two final sessions of three good outcome (GO) and three poor outcome (PO) cases of emotion-focused therapy (EFT) for depression. IMs occurred more often in GO than PO cases. Furthermore, in GO more than PO cases, exploration and insight skills more often preceded action, reflection, and protest IMs in the initial and middle phases of EFT, but more often preceded reconceptualization and performing change IMs in the final phase. Action skills were more often associated with action, reflection, and protest IMs across all phases, especially in the final phase, of GO EFT.

Hybrid Scaffolds for Tissue Regeneration: Chemotaxis and Physical Confinement as Sources of Biomimesis

Biomineralization is a complex ensemble of concomitant phenomena, driving the development of vertebrate and invertebrate organisms, particularly the formation of human bone tissue. In such a process collagen molecules assemble and organize in a complex 3-D structure and simultaneously mineralize with nearly amorphous apatite nanoparticles, whose heterogeneous nucleation, growth, and specific orientation are mediated by various chemical, physical, morphological, and structural control mechanisms, activated by the organic matrix at different size levels. The present work investigates on in-lab biomineralization processes, performed to synthesize hybrid hydroxyapatite/collagen scaffolds for bone and osteochondral regeneration. The synthesis processes are carried out by soft-chemistry procedures, with the purpose to activate all the different control mechanisms at the basis of new bone formation in vivo, so as to achieve scaffolds with high biomimesis, that is, physical, chemical, morphological, and ultrastructural properties very close to the newly formed human bone. Deep analysis of cell behaviour in contact with such hybrid scaffolds confirms their strong affinity with human bone, which in turn determines high regenerative properties in vivo.

Fibrinogen scaffolds with immunomodulatory properties promote in vivo bone regeneration

The hypothesis behind this work is that fibrinogen (Fg), classically considered a pro-inflammatory protein, can promote bone repair/regeneration. Injury and biomaterial implantation naturally lead to an inflammatory response, which should be under control, but not necessarily minimized. Herein, porous scaffolds entirely constituted of Fg (Fg-3D) were implanted in a femoral rat bone defect and investigated at two important time points, addressing the bone regenerative process and the local and systemic immune responses, both crucial to elucidate the mechanisms of tissue remodelling. Fg-3D led to early infiltration of granulation tissue (6 days post-implantation), followed by bone defect closure, including periosteum repair (8 weeks post-injury). In the acute inflammatory phase (6 days) local gene expression analysis revealed significant increases of pro-inflammatory cytokines IL-6 and IL-8, when compared with non-operated animals. This correlated with modified proportions of systemic immune cell populations, namely increased T cells and decreased B, NK and NKT lymphocytes and myeloid cell, including the Mac-1+ (CD18+/CD11b+) subpopulation. At 8 weeks, Fg-3D led to decreased plasma levels of IL-1β and increased TGF-β1. Thus, our data supports the hypothesis, establishing a link between bone repair induced by Fg-3D and the immune response. In this sense, Fg-3D scaffolds may be considered immunomodulatory biomaterials.