Regenerative medicine: then and now--an update of recent history into future possibilities

A double encryption protection algorithm for stem cell bank privacy data based on improved AES and chaotic encryption technology

The unique infinite self-renewal ability and multidirectional differentiation potential of stem cells provide a strong support for the clinical treatment. In light of the growing demands for stem cell storage, how to ensure personal privacy security and comply with strict ethical supervision requirements is particularly important. In order to solve the problem of low security of traditional encryption algorithm, we proposed a double encryption protection (DEP) algorithm for stem cell bank privacy data based on improved AES and chaotic encryption technology. Firstly, we presented the hash value key decomposition algorithm, through the hash value dynamic coding, cyclic shift, conversion calculation to get the key of each subsystem in the built algorithm. Secondly, DEP algorithm for privacy data is realized with two level of encryption. The first level of encryption protection algorithm used AES as the main framework, adding dynamic coding and byte filling based on DNA coding, and carries out dynamic shift of rows and simplified mixing of columns. The second level of encryption protection algorithm conducted random encoding, operation, diffusion and decoding based on the results of our proposed sequence conversion algorithm. Finally, we raised two evaluation indexes, the number of characters change rate (NCCR) and the unified average change intensity of text (UACIT) to measure the sensitivity of encryption algorithms to changes in plain information. The experimental results of using DEP shown that the average values of histogram variance, information entropy, NCCR and UACIT are116.7883, 7.6688, 32.52% and 99.67%, respectively. DEP algorithm has a large key space, high key sensitivity, and enables dynamic encryption of private data in stem cell bank. The encryption scheme provided in this study ensures the security of the private information of stem cell bank in private cloud environment, and also provides a new method for the encryption of similar high confidentiality data.

Bibliometric Analysis of Exercise and Chronic Obstructive Pulmonary Disease

Background

Chronic Obstructive Pulmonary Disease (COPD) is the leading cause of death in the world. Pulmonary rehabilitation includes, but is not limited to, exercise training and education, which aim to improve the physical and psychological conditions of patients with chronic respiratory diseases through self-management interventions.

Objective

The aim of this study was to perform a bibliometric analysis of studies on exercise and COPD published from 2000 to 2021 using VOSviewer and CiteSpace.

Methods

All included literature was obtained from the Web of Science core collection. VOSviewer was used to analyze country or region, institution, major co-cited journals, and keywords. CiteSpace was used to analyze centrality, author and co-cited authors, journals, the strongest citation bursts of references, and keywords.

Results

A total of 1889 articles meeting the criteria were obtained. The United States has the largest number of publications. The American Journal of Respiratory and Critical Care Medicine is the most influential in this field, and the most published research institution is Queen's University. Denis E. O'Donnell has made significant contributions to exercise and COPD research. Association, impact, and statement are hot spots of research in this field.

Conclusion

A bibliometric analysis of exercise interventions for COPD over the past 22 years provides direction for future research.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

Deciphering regeneration through non-model animals: A century of experiments on cephalopod mollusks and an outlook at the future

The advent of marine stations in the last quarter of the 19th Century has given biologists the possibility of observing and experimenting upon myriad marine organisms. Among them, cephalopod mollusks have attracted great attention from the onset, thanks to their remarkable adaptability to captivity and a great number of biologically unique features including a sophisticate behavioral repertoire, remarkable body patterning capacities under direct neural control and the complexity of nervous system rivalling vertebrates. Surprisingly, the capacity to regenerate tissues and complex structures, such as appendages, albeit been known for centuries, has been understudied over the decades. Here, we will first review the limited in number, but fundamental studies on the subject published between 1920 and 1970 and discuss what they added to our knowledge of regeneration as a biological phenomenon. We will also speculate on how these relate to their epistemic and disciplinary context, setting the base for the study of regeneration in the taxon. We will then frame the peripherality of cephalopods in regeneration studies in relation with their experimental accessibility, and in comparison, with established models, either simpler (such as planarians), or more promising in terms of translation (urodeles). Last, we will explore the potential and growing relevance of cephalopods as prospective models of regeneration today, in the light of the novel opportunities provided by technological and methodological advances, to reconsider old problems and explore new ones. The recent development of cutting-edge technologies made available for cephalopods, like genome editing, is allowing for a number of important findings and opening the way toward new promising avenues. The contribution offered by cephalopods will increase our knowledge on regenerative mechanisms through cross-species comparison and will lead to a better understanding of the complex cellular and molecular machinery involved, shedding a light on the common pathways but also on the novel strategies different taxa evolved to promote regeneration of tissues and organs. Through the dialogue between biological/experimental and historical/contextual perspectives, this article will stimulate a discussion around the changing relations between availability of animal models and their specificity, technical and methodological developments and scientific trends in contemporary biology and medicine.

A Paradigm Shift in Tissue Engineering: From a Top–Down to a Bottom–Up Strategy

Tissue engineering (TE) was initially designed to tackle clinical organ shortage problems. Although some engineered tissues have been successfully used for non-clinical applications, very few (e.g., reconstructed human skin) have been used for clinical purposes. As the current TE approach has not achieved much success regarding more broad and general clinical applications, organ shortage still remains a challenging issue. This very limited clinical application of TE can be attributed to the constraints in manufacturing fully functional tissues via the traditional top–down approach, where very limited cell types are seeded and cultured in scaffolds with equivalent sizes and morphologies as the target tissues. The newly proposed developmental engineering (DE) strategy towards the manufacture of fully functional tissues utilises a bottom–up approach to mimic developmental biology processes by implementing gradual tissue assembly alongside the growth of multiple cell types in modular scaffolds. This approach may overcome the constraints of the traditional top–down strategy as it can imitate in vivo-like tissue development processes. However, several essential issues must be considered, and more mechanistic insights of the fundamental, underpinning biological processes, such as cell–cell and cell–material interactions, are necessary. The aim of this review is to firstly introduce and compare the number of cell types, the size and morphology of the scaffolds, and the generic tissue reconstruction procedures utilised in the top–down and the bottom–up strategies; then, it will analyse their advantages, disadvantages, and challenges; and finally, it will briefly discuss the possible technologies that may overcome some of the inherent limitations of the bottom–up strategy.

Regenerative medicine for end-stage fibrosis and tissue loss in the upper aerodigestive tract: a twenty-first century review

OBJECTIVE

This review assesses regenerative medicine of the upper aerodigestive tract during the first two decades of the twenty-first century, focusing on end-stage fibrosis and tissue loss in the upper airways, salivary system, oropharynx and tongue.

METHOD

PubMed, Embase, Google Scholar, Cochrane Library, Medline and clinicaltrials.org were searched from 2000 to 2019. The keywords used were: bioengineering, regenerative medicine, tissue engineering, cell therapy, regenerative surgery, upper aerodigestive tract, pharynx, oropharynx, larynx, trachea, vocal cord, tongue and salivary glands. Original studies were subcategorised by anatomical region. Original human reports were further analysed. Articles on periodontology, ear, nose and maxillofacial disorders, and cancer immunotherapy were excluded.

RESULTS

Of 716 relevant publications, 471 were original studies. There were 18 human studies included, within which 8 reported airway replacements, 5 concerned vocal fold regeneration and 3 concerned salivary gland regeneration. Techniques included cell transplantation, injection of biofactors, bioscaffolding and bioengineered laryngeal structures.

CONCLUSION

Moderate experimental success was identified in the restoration of upper airway, vocal fold and salivary gland function. This review suggests that a shift in regenerative medicine research focus is required toward pathology with a higher disease burden.

Zebrafish (Danio rerio) as a Model for Understanding the Process of Caudal Fin Regeneration

After its introduction for scientific investigation in the 1950s, the cypriniform zebrafish, Danio rerio, has become a valuable model for the study of regenerative processes and mechanisms. Zebrafish exhibit epimorphic regeneration, in which a nondifferentiated cell mass formed after amputation is able to fully regenerate lost tissue such as limbs, heart muscle, brain, retina, and spinal cord. The process of limb regeneration in zebrafish comprises several stages characterized by the activation of specific signaling pathways and gene expression. We review current research on key factors in limb regeneration using zebrafish as a model.

Stem cell therapy: old challenges and new solutions

Stem cell therapy (SCT), born as therapeutic revolution to replace pharmacological treatments, remains a hope and not yet an effective solution. Accordingly, stem cells cannot be conceivable as a "canonical" drug, because of their unique biological properties. A new reorientation in this field is emerging, based on a better understanding of stem cell biology and use of cutting-edge technologies and innovative disciplines. This will permit to solve the gaps, failures, and long-term needs, such as the retention, survival and integration of stem cells, by employing pharmacology, genetic manipulation, biological or material incorporation. Consequently, the clinical applicability of SCT for chronic human diseases will be extended, as well as its effectiveness and success, leading to long-awaited medical revolution. Here, some of these aspects are summarized, reviewing and discussing recent advances in this rapidly developing research field.

Cell sheet tissue engineering for scaffold-free three-dimensional (3D) tissue reconstruction

Three-dimensional (3D) reconstruction of highly functional tissues is of great importance in advancing the clinical benefit of tissue engineering and regenerative medicine. In the last quarter century, many studies have found that by engineering a 3D microenvironment that resembles the in vivo tissue condition, cells exhibit behaviors and functions that reflect those of native tissue. Biomaterial scaffolds are a central technology for providing 3D microenvironments in vitro, and, in conjunction with diverse design and cell seeding advents, have produced highly functional and complex 3D tissues. Here, we describe a new approach to creating 3D cell-dense tissue-like constructs without a biomaterial scaffold. Cell sheet technology with cell sheet layering strategies generates highly cell dense, engineered tissue capable of direct crosstalk with the tissue-engraftment surface, in addition to paracrine-mediated signaling. In this chapter, we will introduce methods of reconstructing 3D tissue using cell sheet technology and the advantages of a scaffold-free design.

Nanotechnology in regenerative ophthalmology

In recent years, regenerative medicine is gaining momentum and is giving hopes for restoring function of diseased, damaged, and aged tissues and organs and nanotechnology is serving as a catalyst. In the ophthalmology field, various types of allogenic and autologous stem cells have been investigated to treat some ocular diseases due to age-related macular degeneration, glaucoma, retinitis pigmentosa, diabetic retinopathy, and corneal and lens traumas. Nanomaterials have been utilized directly as nanoscaffolds for these stem cells to promote their adhesion, proliferation and differentiation or indirectly as vectors for various genes, tissue growth factors, cytokines and immunosuppressants to facilitate cell reprogramming or ocular tissue regeneration. In this review, we reviewed various nanomaterials used for retina, cornea, and lens regenerations, and discussed the current status and future perspectives of nanotechnology in tracking cells in the eye and personalized regenerative ophthalmology. The purpose of this review is to provide comprehensive and timely insights on the emerging field of nanotechnology for ocular tissue engineering and regeneration.

Signals in Stem Cell Differentiation on Fluorapatite-Modified Scaffolds

Previously, we reported that the fluorapatite (FA)-modified polycaprolactone (PCL) nanofiber could be an odontogenic/osteogenic inductive tissue-engineering scaffold by inducing stem cell differentiation and mineralization. The present study aimed to explore which of the signal pathways affected this differentiation and mineralization process. The Human Signal Transduction PathwayFinder RT2 Profiler PCR Array was used to analyze the involvement of potential signal transduction pathways during human dental pulp stem cell (DPSCs) osteogenic differentiation induced by FA-modified PCL nanofiber scaffolds. Based on the results, perturbation studies of the signaling pathways hedgehog, insulin, and Wnt were performed. Moreover, the autophagy process was studied, as indicated by the expression of the microtubule-associated protein 1 light chain 3A/B-II (LC3-II) and the cell osteogenic phenotypic changes. In a comparison of the cells grown on PCL + FA scaffolds and those on PCL-only scaffolds, the transcript expression of BMP2, BMP4, FOXA2, PTCH1, WNT1, and WNT2 (PCR array-labeled signal proteins of the hedgehog pathway); CEBPB, FASN, and HK2 (PCR array-labeled signal proteins of the insulin pathway); and CCND1, JUN, MYC, TCF7, and WISP1 (PCR array-labeled signal proteins of the Wnt pathway) doubled at day 14 when obvious cell osteogenic differentiation occurred. Phenotypically, in all the perturbation groups at day 14, ALP activity, OPN, and autophagy marker LC3-II expression were coincidently decreased. Consistently, no positive alizarin red staining or von Kossa staining was observed in the specimens from these perturbation groups at day 28. The results showed that when obvious cell differentiation occurred at day 14 on PCL + FA control groups, the inhibition of the hedgehog, insulin, and Wnt pathways significantly decreased DPSC osteogenic differentiation and mineralization. The osteogenic differentiation of DPSCs grown on FA-modified PCL scaffolds appeared to be positively modulated by the hedgehog, insulin, and Wnt signal pathways, which were coordinated with and/or mediated by the cell autophagy process.

Heterogeneity of Scaffold Biomaterials in Tissue Engineering

Tissue engineering (TE) offers a potential solution for the shortage of transplantable organs and the need for novel methods of tissue repair. Methods of TE have advanced significantly in recent years, but there are challenges to using engineered tissues and organs including but not limited to: biocompatibility, immunogenicity, biodegradation, and toxicity. Analysis of biomaterials used as scaffolds may, however, elucidate how TE can be enhanced. Ideally, biomaterials should closely mimic the characteristics of desired organ, their function and their in vivo environments. A review of biomaterials used in TE highlighted natural polymers, synthetic polymers, and decellularized organs as sources of scaffolding. Studies of discarded organs supported that decellularization offers a remedy to reducing waste of donor organs, but does not yet provide an effective solution to organ demand because it has shown varied success in vivo depending on organ complexity and physiological requirements. Review of polymer-based scaffolds revealed that a composite scaffold formed by copolymerization is more effective than single polymer scaffolds because it allows copolymers to offset disadvantages a single polymer may possess. Selection of biomaterials for use in TE is essential for transplant success. There is not, however, a singular biomaterial that is universally optimal.

The potential role of telocytes in Tissue Engineering and Regenerative Medicine

Research and ideas for potential applications in the field of Tissue Engineering (TE) and Regenerative Medicine (RM) have been constantly increasing over recent years, basically driven by the fundamental human dream of repairing and regenerating lost tissue and organ functions. The basic idea of TE is to combine cells with putative stem cell properties with extracellular matrix components, growth factors and supporting matrices to achieve independently growing tissue. As a side effect, in the past years, more insights have been gained into cell-cell interaction and how to manipulate cell behavior. However, to date the ideal cell source has still to be found. Apart from commonly known various stem cell sources, telocytes (TC) have recently attracted increasing attention because they might play a potential role for TE and RM. It becomes increasingly evident that TC provide a regenerative potential and act in cellular communication through their network-forming telopodes. While TE in vitro experiments can be the first step, the key for elucidating their regenerative role will be the investigation of the interaction of TC with the surrounding tissue. For later clinical applications further steps have to include an upscaling process of vascularization of engineered tissue. Arteriovenous loop models to vascularize such constructs provide an ideal platform for preclinical testing of future therapeutic concepts in RM. The following review article should give an overview of what is known so far about the potential role of TC in TE and RM.

The Potential Role of Telocytes for Tissue Engineering and Regenerative Medicine

Despite recent advances in surgery, medicine and anaesthesiology as well as the development of microsurgical tissue transplantation, wear out of body parts remains a problem, and organ shortage does not allow to allocate enough donor organs for patients with vital diseases and conditions. The idea to create spare parts or spare organs from the patients own cells by combining engineering approaches to cellular and molecular medicine for th purpose of Tissue Engineering (TE) was fascinating when popularized in the early 1990ies. However clinically success was limited, mainly because of a lack in rapid vascularization of large scale TE replacement constructs useful for clinical purposes. The idea to utilize cells and cytokines to aid the human organism in gradually restoring lost tissue functions has drawn attention to the wider field of Regenerative Medicine (RM). Stem cells and putative stem cells, such as the recently discovered and meanwhile well described interstitial Telocytes, which are comprised of extremely long and thin prolongations named telopodes, may well become active players in the regenerative process. This article highlights the principles of TE and RM and the potential role of Telocytes with regard to tissue regeneration.

Tissue engineering in burn scar reconstruction

Nowadays, most patients with severe burns will survive their injury. This evolution is accompanied by the challenge to cover a large percentage of total body surface area burned. Consequently, more and more patients have to deal with the sequelae of burn scars and require (multiple) reconstructions. This review provides a gross overview of developments in the field of tissue engineering for permanent burn wound coverage and reconstructive burn surgery, focusing on usage and clinical effectiveness. Not only skin substitutes will be discussed but also the replacement of subcutaneous fat tissue and cartilage.

Severe mutilating injuries with complex macroamputations of the upper extremity - is it worth the effort?

Introduction

An amputation of the upper extremity and the following replantation is still one of the most challenging operations in the field of reconstructive surgery, especially in extremely severe cases of combined mutilating macroamputations including avulsion and multilevel injuries. Specialists agree that macroamputations with sharp wound edges are an absolute indication for replantation. However, there is no agreement in disastrous cases including avulsion and multilevel injuries. The outcome of the operation is depending on several factors, including the type of accident, age and pre-existing disease of the patient, as well as time of ischemia and appropriate physical therapy.

Methods

Between January 1^st 2003 and December 31^st 2011 six patients underwent a macroreplantation with disastrous combined and complex injuries of the upper extremity in our department. We performed a follow up and evaluated the functional outcome of the upper extremity function using the DASH questionnaire (average follow up of 3.1 years).

Results

The mean time of ischemia was 04:50 h (02:46 h–06:17 h). The mean time for the operation was 05:30 h (01:55 h–08:20 h). The mean operations needed per patient were 7 (2–16). The average hospital stay was 29d (16–59d). According to the DASH-Score from five out of six patients the functional outcome of the replanted extremity has a mean score of 71 points. The versatility of the replanted extremity in the field of work had 95, and sport, music was assessed with a mean score of 96 points.

Conclusions

Severe and disastrous combined and complex macroamputations of the upper extremity may also have an absolute indication for replantation even though the functional outcome is poor. Not only the feeling of physical integrity can be restored, but the replantation of an amputated upper extremity enables complete or partial recovery of function and sensibility of the arm which is important for the individual. Although our results show a very high DASH-Score, those achievements justify time and person consuming operations. In most cases a replanted extremity is still superior to a secondary allotransplantation. Usually the use of prosthesis is not favored by the treated patients.

Emerging Imaging Modalities in Regenerative Medicine

The field of regenerative medicine has experienced considerable growth in recent years as the translation of pre-clinical biomaterials and cell- and gene-based therapies begin to reach clinical application. Until recently, the ability to monitor the serial responses to therapeutic treatments has been limited to post-mortem tissue analyses. With improvements in existing imaging modalities and the emergence of hybrid imaging systems, it is now possible to combine information related to structural remodeling with associated molecular events using non-invasive imaging. This review summarizes the established and emerging imaging modalities that are available for in vivo monitoring of clinical regenerative medicine therapies and discusses the strengths and limitations of each imaging modality.

Fluorapatite-modified scaffold on dental pulp stem cell mineralization

In previous studies, fluorapatite (FA) crystal-coated surfaces have been shown to stimulate the differentiation and mineralization of human dental pulp stem cells (DPSCs) in two-dimensional cell culture. However, whether the FA surface can recapitulate these properties in three-dimensional culture is still unknown. This study examined the differences in behavior of human DPSCs cultured on electrospun polycaprolactone (PCL) NanoECM nanofibers with or without the FA crystals. Under near-physiologic conditions, the FA crystals were synthesized on the PCL nanofiber scaffolds. The FA crystals were evenly distributed on the scaffolds. DPSCs were cultured on the PCL+FA or the PCL scaffolds for up to 28 days. Scanning electron microscope images showed that DPSCs attached well to both scaffolds after the initial seeding. However, it appeared that more multicellular aggregates formed on the PCL+FA scaffolds. After 14 days, the cell proliferation on the PCL+FA was slower than that on the PCL-only scaffolds. Interestingly, even without any induction of mineralization, from day 7, the upregulation of several pro-osteogenic molecules (dmp1, dspp, runx2, ocn, spp1, col1a1) was detected in cells seeded on the PCL+FA scaffolds. A significant increase in alkaline phosphatase activity was also seen on FA-coated scaffolds compared with the PCL-only scaffolds at days 14 and 21. At the protein level, osteocalcin expression was induced only in the DPSCs on the PCL+FA surfaces at day 21 and then significantly enhanced at day 28. A similar pattern was observed in those specimens stained with Alizarin red and Von Kossa after 21 and 28 days. These data suggest that the incorporation of FA crystals within the three-dimensional PCL nanofiber scaffolds provided a favorable extracellular matrix microenvironment for the growth, differentiation, and mineralization of human DPSCs. This FA-modified PCL nanofiber scaffold shows promising potential for future bone, dental, and orthopedic regenerative applications.

Management of chronic osteomyelitis of the tibia with life-threatening complications under negative pressure wound therapy and isolation of Helcococcus kunzii

We report the case of an 86-year-old man with severe wound infection originating from a chronic crural ulcer of the lower limb, which under negative pressure wound therapy led to excessive tissue necrosis and perforation of the anterior tibial artery. A swab taken 10 and 7 days preoperatively was positive for Helcococcus kunzii. H. kunzii has been described as a potentially pathogenic organism. The questions whether the negative pressure wound therapy itself caused the bleeding or the negative pressure wound therapy, which generates an anaerobic atmosphere, has triggered the growth and invasion of the facultative anaerobic bacterium H. kunzii and owing to the infection the artery perforated or whether the bacteria has no influence at all remain currently unanswered. After surgical debridement the signs of infection were completely eliminated, and a free musculocutaneous flap led to rapid healing of the wound. Following which H. kunzii was no longer detectable.

Management of multicellular senescence and oxidative stress

Progressively sophisticated understanding of cellular and molecular processes that contribute to age-related physical deterioration is being gained from ongoing research into cancer, chronic inflammatory syndromes and other serious disorders that increase with age. Particularly valuable insight has resulted from characterization of how senescent cells affect the tissues in which they form in ways that decrease an organism's overall viability. Increasingly, the underlying pathophysiology of ageing is recognized as a consequence of oxidative damage. This leads to hyperactivity of cell growth pathways, prominently including mTOR (mammalian target of rapamycin), that contribute to a build-up in cells of toxic aggregates such as progerin (a mutant nuclear cytoskeletal protein), lipofuscin and other cellular debris, triggering formation of senescent cellular phenotypes, which interact destructively with surrounding tissue. Indeed, senescent cell ablation dramatically inhibits physical deterioration in progeroid (age-accelerated) mice. This review explores ways in which oxidative stress creates ageing-associated cellular damage and triggers induction of the cell death/survival programs' apoptosis, necrosis, autophagy and 'necroapoptophagy'. The concept of 'necroapoptophagy' is presented here as a strategy for varying tissue oxidative stress intensity in ways that induce differential activation of death versus survival programs, resulting in enhanced and sustained representation of healthy functional cells. These strategies are discussed in the context of specialized mesenchymal stromal cells with the potential to synergize with telocytes in stabilizing engrafted progenitor cells, thereby extending periods of healthy life. Information and concepts are summarized in a hypothetical approach to suppressing whole-organism senescence, with methods drawn from emerging understandings of ageing, gained from Cnidarians (jellyfish, corals and anemones) that undergo a unique form of cellular regeneration, potentially conferring open-ended lifespans.

Experimental total wrapping of breast implants with acellular dermal matrix: a preventive tool against capsular contracture in breast surgery?

BACKGROUND

Capsular contracture remains a hitherto unsolved complication after implantation of silicone gel-filled breast prostheses. Based on clinical and experimental data, the use of an acellular dermal matrix as a sheath around implants may lead to lesser capsular contracture acting as a proposed biological environment mimicking wound bed tissue. The aim of our study was to analyse the tissue reaction after implantation of silicone prosthesis with and without an envelope of acellular dermal matrix.

METHODS

Implantation of 60 silicone prostheses in the back of Lewis rats were carried out, randomly paired taking one rat from group A and one from group B. Group A included implants completely enveloped with xenogenic acellular dermis and group B undraped silicone implants. At 3, 6 and 12 weeks postoperatively, the samples were explanted and subjected to histological and immunohistochemical evaluation.

RESULTS

A new myofibroblast tissue layer was identified in proximity to the implant in both groups. The thickness of the layer in group A was continuously thinner than in group B regarding the different explantation time points. Implants completely wrapped with acellular dermal matrix showed significantly lesser inflammatory signs at 3 and 12 weeks after implantation compared to controls. Cell proliferation after 12 weeks was significantly decreased in group A.

CONCLUSION

The slight myofibroblast layer and reduced rate of inflammation and proliferation in the treatment group show a positive effect of total acellular dermal matrix envelope and hypothesise the decrease of capsular contracture in long-term periods.

Detecting of breast cancer metastasis by means of regional lymph node sampling during autologous breast reconstruction--a screening of 519 consecutive patients

Background

The internal mammary artery and vein is often used as a site of anastomoses in microvascular breast reconstruction. This area supports lymphatic drainage of the breast and its role in breast cancer metastasis remains unclear. We hypothesize that sampling of internal mammary lymph nodes at the time of microvascular anastomoses preparation may identify persistent or recurrent local disease and mandate the need for additional treatment in this area.

Material/Methods

A retrospective chart review from 519 patients in the time between January 2006 and September 2009 was performed on all patients who underwent internal mammary lymph node sampling at the time of microvascular breast reconstruction.

Results

Microvascular breast reconstruction was performed in 519 patients. Enlarged internal mammary lymph nodes were found and harvested in 195 patients for histological review. Six of 195 (3.08%) were found positive for metastatic disease requiring additional oncologic treatment.

Conclusions

The internal mammary lymphatic drainage system is an important and often underappreciated pathway for breast metastasis. Routine sampling of these lymph nodes at the time of microvascular breast reconstruction is easy to perform and is a useful tool to identify women, who might require additional treatment and increase cancer-free survival.

Tissue engineering and regenerative medicine -where do we stand?

Tissue Engineering (TE) in the context of Regenerative Medicine (RM) has been hailed for many years as one of the most important topics in medicine in the twenty-first century. While the first clinically relevant TE efforts were mainly concerned with the generation of bioengineered skin substitutes, subsequently TE applications have been continuously extended to a wide variety of tissues and organs. The advent of either embryonic or mesenchymal adult stem-cell technology has fostered many of the efforts to combine this promising tool with TE approaches and has merged the field into the term Regenerative Medicine. As a typical example in translational medicine, the discovery of a new type of cells called Telocytes that have been described in many organs and have been detected by electron microscopy opens another gate to RM. Besides cell-therapy strategies, the application of gene therapy combined with TE has been investigated to generate tissues and organs. The vascularization of constructs plays a crucial role besides the matrix and cell substitutes. Therefore, novel in vivo models of vascularization have evolved allowing axial vascularization with subsequent transplantation of constructs. This article is intended to give an overview over some of the most recent developments and possible applications in RM through the perspective of TE achievements and cellular research. The synthesis of TE with innovative methods of molecular biology and stem-cell technology appears to be very promising.

Stem cells in gynecology

Stem cell based therapies hold promise for the obstetrician and gynecologist. This article reviews the history of stem cells and some of their current applications in gynecology. Currently, mesenchymal and muscle-derived stem cells are being explored for the treatment of urinary and anal incontinence. Potential stem cell treatments include fistula repair, vaginal tissue engineering, and graft material enhancement. Published animal and human pilot studies demonstrate improved histologic and functional outcomes in those receiving stem cells. Transplanted cells may improve function by local engraftment, trophic factors, or modulation of inflammation. Further clinical and safety studies are needed before clinical application.

Three-dimensional in vitro tri-culture platform to investigate effects of crosstalk between mesenchymal stem cells, osteoblasts, and adipocytes

The bone marrow niche for mesenchymal stem cells (MSCs) contains different amounts of bone and fat that vary with age and certain pathologies. How this dynamic niche environment may affect their differentiation potential and/or healing properties for clinical applications remains unknown, largely due to the lack of physiologically relevant in vitro models. We developed an enabling platform to isolate and study effects of signaling interactions between tissue-scale, laminated hydrogel modules of multiple cell types in tandem. We applied this platform to co- and tri-culture of primary human MSCs, osteoblasts, and adipocytes over 18 days in vitro. Each cell type was analyzed separately with quantitative polymerase chain reaction (qPCR) and histochemistry for several mesenchymal lineage markers. Distinct expression dynamics for osteogenic, adipogenic, chondrogenic, and myogenic transcriptional regulators resulted within each cell type depending on its culture setting. Incorporating this data into multivariate models produced latent identifiers of each emergent cell type dependent on its co- or tri-culture setting. Histological staining showed sustained triglyceride storage in adipocytes regardless of culture condition, but transient alkaline phosphatase activity in both osteoblasts and MSCs. Taken together, our results suggest novel emergent phenotypes for MSCs, osteoblasts, and adipocytes in bone marrow that are dependent on and result in part from paracrine interactions with their neighboring cell types.

Emerging trends in regenerative medicine: a scientometric analysis in CiteSpace

INTRODUCTION

Regenerative medicine involves research in a number of fields and disciplines such as stem cell research, tissue engineering and biological therapy in general. As research in these areas advances rapidly, it is critical to keep abreast of emerging trends and critical turns of the development of the collective knowledge.

AREAS COVERED

A progressively synthesized network is derived from 35,963 original research and review articles that cite 3875 articles obtained from an initial topic search on regenerative medicine between 2000 and 2011. CiteSpace is used to facilitate the analysis of the intellectual structure and emerging trends.

EXPERT OPINION

A major ongoing research trend is concerned with finding alternative reprogramming techniques as well as refining existing ones for induced pluripotent stem cells (iPSCs). A more recent emerging trend focuses on the structural and functional equivalence between iPSCs and human embryonic stem cells and potential clinical and therapeutic implications on regenerative medicine in a long run. The two trends overlap in terms of what they cite, but they are distinct and have different implications on future research. Visual analytics of the literature provides a valuable, timely, repeatable and flexible approach in addition to traditional systematic reviews so as to track the development of new emerging trends and identify critical evidence.

Free vascularized metacarpal bone graft combined with extended dorsal metacarpal artery flap for phalangeal bone and soft tissue loss: case report

A 45-year-old man suffered from a complex bone and soft tissue defect of the middle phalanx of his left middle finger after an electric saw injury. Here, we present the patient's clinical and radiological outcomes after reconstruction with a free vascularized metacarpal II bone graft and an extended distally based second dorsal metacarpal artery skin flap (DMCA). To our knowledge, this is the first description of a free vascularized metacarpal bone graft combined with DMCA for distal finger reconstruction.

Identification of telocytes in skeletal muscle interstitium: implication for muscle regeneration

Skeletal muscle interstitium is crucial for regulation of blood flow, passage of substances from capillaries to myocytes and muscle regeneration. We show here, probably, for the first time, the presence of telocytes (TCs), a peculiar type of interstitial (stromal) cells, in rat, mouse and human skeletal muscle. TC features include (as already described in other tissues) a small cell body and very long and thin cell prolongations-telopodes (Tps) with moniliform appearance, dichotomous branching and 3D-network distribution. Transmission electron microscopy (TEM) revealed close vicinity of Tps with nerve endings, capillaries, satellite cells and myocytes, suggesting a TC role in intercellular signalling (via shed vesicles or exosomes). In situ immunolabelling showed that skeletal muscle TCs express c-kit, caveolin-1 and secrete VEGF. The same phenotypic profile was demonstrated in cell cultures. These markers and TEM data differentiate TCs from both satellite cells (e.g. TCs are Pax7 negative) and fibroblasts (which are c-kit negative). We also described non-satellite (resident) progenitor cell niche. In culture, TCs (but not satellite cells) emerge from muscle explants and form networks suggesting a key role in muscle regeneration and repair, at least after trauma.

[Upper and lower eyelid blepharoplasty : development of aesthetic periocular plastic surgery]

The article describes the indications and techniques for blepharoplasty of the upper and lower eyelids as well as combinations with other eyelid correction techniques. Upper eyelid blepharoplasty may include skin excision with orbital fat modulation as well as ptosis correction and definition of the superior sulcus palpebralis. The main goal of lower lid blepharoplasty is modulation of intraseptal fat and also often the treatment of a lower lid laxity by canthopexy. It is recommended to avoid excessive skin resection in the lower lid. Furthermore techniques to address an ectropium are reviewed and possible complications of blepharoplasty are presented.

Heterocellular communication in the heart: electron tomography of telocyte-myocyte junctions

Myocardium is composed of two main cell populations: cardiomyocytes (CMs) and interstitial cells (e.g. fibroblasts, immunoreactive cells, capillaries). However, very recently we have showed that a novel type of interstitial cell called telocytes (TCs) does exist in epi-, myo- and endocardium. They have very long and thin telopodes (Tp) formed by alternating podomeres and podoms. Heterocellular communication between TCs and CMs it is supposed to occur by shed vesicles and close apposition. If TCs have to play a role in cardiac physiology it is expected to develop direct and unambiguous contacts with CMs. Because a clear membrane-to-membrane junction has not been reported by electron microscopy we have investigated the heterocellular communication in the mouse heart by electron tomography. This advanced technique showed that small dense structures (10-15 nm nanocontacts) directly connect TCs with CMs. More complex and atypical junctions could be observed between TCs and CMs at the level of intercalated discs. This study proves that TCs and CMs are directly connected and might represent a 'functional unit'.

Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy

This study describes a novel type of interstitial (stromal) cell — telocytes (TCs) — in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles.