1- Introduction

2- Mechanisms regulating MSC differentiation

3- Pericytes as pre-programmed MSC precursors in vivo

4- Discussion and future considerations

References

Abstract

The increasing application of approaches that allow tracing of individual cells over time, together with transcriptomic and epigenomic analyses is changing the way resident stromal stem cells (mesenchymal stem cells) are viewed. Rather than being a defined, homogeneous cell population as described following in vitro expansion, in vivo, these cells are highly programmed according to their resident tissue location. This programming is evidenced by different epigenetic landscapes and gene transcription signatures in cells before any in vitro expansion. This has potentially profound implications for the heterotypic use of these cells in therapeutic tissue engineering applications.

Introduction

The prototypical mesenchymal stem cell (MSC), isolated from bone marrow (BM) was described over 3 decades ago by Friedenstein [1]. This characterisation was later expanded to include a cell type, isolated from connective tissue stroma that can exhibit stem cell properties in vitro [2, 3]. These observations led many researchers to identify cells in multiple organs that had a similar immunophenotype and characteristic s in vitro of MSCs in that they could be differentiated to form osteoblast -like, chondrocyte -like, and adipocyte -like cells. Tissues included, connective tissue of teeth [4, 5] , muscle [6], adipose [7], dermis [8], heart and liver [9]. These cell populations expressed a number of the by now established MSC gene markers and all shared some common characteristics including morphology, adherence to tissue culture plastic, and trilineage differentiation [9, 10].

Somatic stem cells expand massively during tissue regeneration, which might require control of cell fitness, allowing elimination of non-competitive, potentially harmful cells. How or if such cells are removed to restore organ function is not fully understood. Here, we show that a substantial fraction of muscle stem cells (MuSCs) undergo necroptosis because of epigenetic rewiring during chronic skeletal muscle regeneration, which is required for efficient regeneration of dystrophic muscles. Inhibition of necroptosis strongly enhances suppression of MuSC expansion in a non-cell-autonomous manner. Prevention of necroptosis in MuSCs of healthy muscles is mediated by the chromatin remodeler CHD4, which directly represses the necroptotic effector Ripk3, while CHD4-dependent Ripk3 repression is dramatically attenuated in dystrophic muscles. Loss of Ripk3 repression by inactivation of Chd4 causes massive necroptosis of MuSCs, abolishing regeneration. Our study demonstrates how programmed cell death in MuSCs is tightly controlled to achieve optimal tissue regeneration.

Introduction

Skeletal muscle regeneration provides a paradigmatic example for the decisive role of tissue-resident stem cells and the necessity of cellular interactions to achieve organ restoration. Muscle stem cells (MuSCs; also known as satellite cells) are indispensable for muscle regeneration but require assistance and instructions from fibroblasts, endothelial cells, fibroadipogenic progenitor cells (FAPs), and immune cells, among others (Charge´ and Rudnicki, 2004; Tidball, 2011; Relaix and Zammit, 2012). Such cells not only provide critical support for MuSCs, enabling their expansion, but might also promote secondary cell death (Saclier et al., 2013; Latroche et al., 2015; Tidball and Villalta, 2010; Joe et al., 2010; Forbes and Rosenthal, 2014). Secondary cell death is not necessarily harmful but might elicit beneficial effects. For example, programmed cell death in FAPs, induced by TNFreleasing inflammatory macrophages, limits fibrosis in acutely damaged skeletal muscles (Lemos et al., 2015). Moreover, MuSCs might engage in a battle of the ‘‘survival of the fittest’’ to ensure that damaged or less fit stem cells are eliminated (Bowling et al., 2019). It has been proposed that tissue stem cells are routinely lost and replaced in a process called neutral cell competition, but many questions related to such a machinery, including the mechanisms by which unfit cells are removed, have yet to be answered (Klein and Simons, 2011). At present, it is not known whether and to what extent MuSCs succumb to programmed cell death in acutely damaged and continuously regenerating dystrophic muscles.

1- BACKGROUND

2- IN VIVO T‐ CELL DEPLETION: ALEMTUZUMAB AND ANTI‐THYMOCY TE GLOBULIN

3- COSTIMUL ATORY BLOCK ADE: ABATACEPT AND ALEFACEPT

4- PROTE A SOME INHIBITORS: BORTEZOMIB AND IXAZOMIB

6- B‐ CELL MODUL ATION: RITUXIMAB, OFATUMUMAB, BTK /ITK , AND SYK INHIBITORS

7- JANUS KINA SE INHIBITORS: RUXOLITINIB, BARICITINIB, AND ITACITINIB

8- INDUC TION OF IMMUNE TOLER ANCE: E X TR ACORPORE AL PHOTOPHERESIS AND INTERLEUKIN‐2

9- CELLULAR THERAPIES

10- HOW TO MANAGE CGVHD

11- CONCLUSION

12- FUTURE PERSPECTIVE

REFERENCES

Abstract

Chronic Graft Versus Host Disease (cGVHD) occurs in over 50‐70% of patients un‐ dergoing hematopoietic stem‐cell transplantation (HSCT) and is the leading cause of late non‐relapse mortality. cGVHD typically has insidious multi‐organ involvement and has been associated with a worse quality of life, functional status, and increased risk of subsequent comorbidities. The last several years have seen advances in the understanding of the disease, which provided a framework for the design of transla‐ tional and clinical studies with newer agents currently at different phases which that may hopefully change the course of the disease. This review provides an overview of more commonly used and newer second line options for the management of cGVHD.

BACKGROUND

Chronic Graft‐Versus‐Host Disease (cGVHD) occurs in over 30%‐70% of patients undergoing hematopoietic stem‐cell transplan‐ tation (HSCT)1 and is the leading cause of late nonrelapse mortality.2 Furthermore, cGVHD has been associated with a worse quality of life, functional status, and increased risk of subsequent comorbidi‐ ties. Unfortunately, advances in the practice of HSCT over the last several years have not decreased the incidence or severity of this complication.3 This is thought to be at least in part due to increased survival after HSCT and the use of pooled peripheral blood mono‐ nuclear cells. Thus, although many GVHD prevention regimens have reduced the incidence of acute graft‐versus‐host disease (aGVHD), cGVHD has been less affected.4 Chronic GVHD typically has insidious multi‐organ involvement, predominantly of mucocutaneous tissues. This defines two different and typical clinical presentations: lichen planus‐like or lichenoid and sclerodermatous. The lichenoid form resembles lichen planus, with a similar pattern of involvement of cutaneous and mucosal tissues. Sclerodermatous cGVHD is a fibroproliferative disease that when severe can involve the joints with potentially severe impact on mo‐ bility.

2- Tumour-Associated Macrophage (TAM)

3- Phenotypical Distinction of Macrophage Subtypes

4- TAM in Colon Tumour

5- Potential Candidates to Reeducate TAM

6- Conclusion

References

Introduction

Colorectal cancer (CRC), also known as bowel cancer or colon cancer, is a type of cancer that begins its abnormal cell growth in the colon or rectum part of the large intestine. In men, CRC has been reported to be the third most common case to occur. On the other hand, it is the second most commonly occurring cancer incidence among women in the world [1, 2]. According to Ferlay et al. [3], approximately 1.36 million people around the world have been affected with cancer. As shown in Table 1, in the United States of America (USA) alone, it is estimated that about 71,420 and 64,010 new CRC cases will be reported among males and females, respectively [4]. Meanwhile, in Asian countries, the disease has become one of the major health concerns in which the number of CRC cases being reported is increasing in an alarming state [5]. Among Asian countries, Japan has been recorded to have the highest incidence of CRC, followed by Hong Kong [6, 7]. Malaysia, in particular, has categorised CRC to be its second most common cancer reported. Table 2 shows that ethnic Chinese holds the highest incidence rate per 100,000 (27.35), followed by Malay (18.95), and Indian (17.55) [8]. Several risk factors have been identified to be associated with the development of CRC. Obesity, lack of physical activity, tobacco use, moderate-to-heavy alcohol consumption, hypertension, abnormal blood lipids, and colonisation of Streptococcus gallolyticus (S. gallolyticus) are said to be the exogenous risk factors. Conversely, personal or familial history of colorectal polyps, inherited CRC syndromes (e.g., hereditary nonpolyposis colon cancer (HNPCC) and Cowden’s disease), inflammatory bowel disease, and type 2 diabetes are said to be the endogenous risk factors [9–11]. As shown in Figure 1, in the presence of exogenous and/or endogenous risk factors, cancer development might occur if the risk factors managed to interact synergistically [12].

1- Introduction

2- Materials

3- Method

4- Results and discussion

5- Conclusions

References

Abstract

In this research, a novel hybrid material bone implant manufacturing through the integration of two materials using additive manufacturing (AM) technology is proposed. Biomimetic application can manufacture high strength biomechanical implants with optimised geometry and mass. The combination of polymers allows a significant leap in the development and production of a great diversity of components and applications of biomaterials. A novel hybrid scaffold with a poly lactic acid (PLA) matrix reinforced with carbohydrate particles (cHA) is analysed using digital surface software in the mass proportions of 100/0, 95/5, 90/10 and 80/20 for application in tissue and regenerative engineering, seeking a higher proposition strength of PLA. Filaments are used to fabricate scaffolds by 3D printing, using the fused deposition method. The frameworks are submitted to bioactivity tests, surface roughness evaluation, apparent porosity and mechanical analysis. Analysis of the microstructure of the composite particle evaluates the 3D surface luminance structure and the profile structure. Cross-sectional views of the specimens are extracted and analysed, and the surface roughness, waviness profile, and Gaussian filter of the structures are observed. In summary the structures are checked and analysed by SEM and EDS where possible, to observe the bioactive behaviour of the materials. The relationship between cHA content and roughness is shown to be proportional. The mechanical properties are shown to be affected by the reduced interaction between the PLA matrix and the cHA particles.

1- Introduction

Findings from population statistical research institutes point to a rising life expectancy in the world population. As humans age, the risk of compromising organs, tissues and the body as a whole increases. Tissue engineering seeks to use biomaterials to replace conventional transplants. A biomaterial is defined as any substance or combination of materials, other than drugs or synthetic natural materials, which can be used, for any period, to partially substitute for any tissue, organ or function of the body for the purpose of maintaining or improving the lifespan of an individual [1]. A fundamental requirement of a biomaterial used in clinical medicine is that it is biocompatible, that is, it can coexist with human tissue without causing any undesirable or inappropriate effects [2, 3]. Biomaterials can be classified into three main categories: bioinert, intolerant materials that are not capable of inducing any biological interfacial bond between the implant and the host tissue [4, 5]; bioactive, capable of interacting with body tissues, forming chemical or biological bonds and favouring the development of processes such as implant fixation, colonisation and tissue regeneration; and bioreabsorbable, materials that are gradually reabsorbed until they disappear entirely and are wholly replaced by new tissue in vivo. In general, biomaterials can be classified into: natural, from plants and animals; and synthetic, which can be sub-categorised into metals, synthetic polymers, ceramics and composites [6, 7].

Introduction

Materials and Methods

Results

Discussion

Conclusions

References

Introduction

Mesenchymal stem cells (MSCs) have been isolated from various fetal and adult organs. Friedenstein et al. [1–3] frst described mouse bone marrow MSCs and their multilineage diferentiation potential. Te multilineage diferentiation potential of adult human MSCs from bone marrow was described by Pittenger et al. [4]. Since then, human MSCs from various organs have been described and transplanted clinically in multiple felds of applications [5, 6]. For autologous transplantation, the foremost important practical aspect is for certain the ease of sourcing. Tis makes adipose, skin, or bone marrow a more obvious choice than, for example, liver, placenta, or umbilical cord. Adipose tissuederived MSCs can be obtained by liposuction under general anesthesia, while an iliac crest bone marrow sample can be obtained in a physician’s ofce under local anesthetic. Tis makes obtaining bone marrow MSCs much less invasive than adipose-derived MSCs. Another important aspect for clinical applications is the potentially diferent capability of MSCs from diferent tissues to support the local environment by the release of growth factor and cytokines. More recently, the release of exosomes and microvesicles from MSCs has been investigated for cell-free therapies (for review, see [7]). A variety of diferent growth factors, cytokines, exosomes, and microvesicles have been found to be secreted or taken up by human MSCs; sphingolipids and their receptors were shown to contribute to MSCs functioning and to regulate the course of transplantation (for reviews, see [8–10]). For example, Schinkothe et al. [11] analyzed 120 cytokines and ¨ growth factors in the cell culture medium of human bone marrow-derived MSCs. From these, 44 were found to be secreted into the medium and 40 were taken up from the medium. Shen et al. [12] analyzed 16 growth factors and cytokines that were secreted by human umbilical cordderived MSCs. Efects of transplantation of MSCs have not been only related to the release of growth factors and cytokines, but also to mitochondrial transfer [13] as well as fusion [14, 15] of donor MSCs with host cells. For allogenic MSC transplantation, the option to remove donor MSCs afer patient recovery is of interest in order to avoid long-term efects due to potential cell fusion and immunological complications. Te encasement of MSCs should occur in porous structures with adequate pore sizes as to allow the unrestricted release of secreted molecules but to prevent cell release. Diferent methods for encapsulation of cells for transplantation were described; cells have been commonly encapsulated in alginate [16–20] or other types of gel-like embedding matrices [21– 23], but unusual approaches included, for example, the use of silk [24]. We developed a semipermeable membrane hollowfber assembly that provides adequate and adjustable pore sizes, allows for easy flling, can be variable in length to accommodate various amounts of cells, allows for potential removal of cells if necessary, and is made of biomedical grade materials that have been applied in vivo and in vitro.

2- Methods

3- Results

4- Discussion and Conclusions

References

Introduction

Breast cancer is among the top causes of disability of older women globally [1]. It accounts for 30% of the total cancer cases and 15% of cancer deaths [2, 3].Te use of more efective and less toxic medications has resulted in an increasing rate of survivorship among women with breast cancer, with the relative survival rate at 10 years afer diagnosis for combined stages of breast cancer being over 80% in the United States [4]. Moreover, breast cancer survivors have a higher risk of developing a future cancer than individuals who have no prior cancer history [5, 6]. Tis large and growing population calls for increasing attention to clinical decision-making in the cancer care context in terms of beliefs about prevention and control of recurrence for those who survive their initial breast cancer. Te Institute of Medicine has established Survivorship Care Plans (SCPs) as a critical component of cancer care that should be provided to cancer survivors upon completion of treatment. SCPs can include follow-up screening, signs of recurrence, monitoring and managing psychosocial efects, guidelines for lifestyle modifcations and health promotion activities, and empowering cancer survivors to support for their own healthcare needs [7, 8].

Background: Rheumatoid arthritis (RA) is a complex inflammatory disease that modifies body composition. Although body mass index (BMI) is one of the clinical 48 nutrition tools widely used to assess indirectly nutritional status, it is not able to identify these body alterations. Bioelectrical Vector Analysis (BIVA) is an alternative method to assess hydration and body cell mass of patients with wasting conditions. Objective: To investigate the differences in nutrition status according to BMI groups (normal, overweight and obesity) and BIVA classification (cachectic and non-cachectic) in women with RA. Methods: Women with confirmed diagnosis of RA were included from January 2015 to June 2016. Whole-body bioelectrical impedance was measured using a tetrapolar and mono-frequency equipment. Patients were classified according to BMI as: low body weight (n=6, 2.7%), normal (n=59, 26.3%), overweight (n=88, 39.3%) and obese (n=71, 31.7%), and each 58 group was divided into BIVA groups (cachectic 51.8% and non-cachectic 48.2%). Results: A total of 224 RA patients were included, with mean age 52.7 years and 60 median disease duration of 12 years. Significant differences were found in weight, 61arm circumference, waist, hip, resistance/height, reactance/height and erythrocyte sedimentation rate among all BMI groups. However, serum albumin levels were significantly different between cachectic and non-cachectic patients independently of BMI. In all BMI categories, cachectic groups had lower reactance and phase angle than non-cachectic subjects. Conclusion: RA patients with normal or even high BMI have a significantly lower muscle component. Evaluation of body composition with BIVA in RA patients could be an option for cachexia detection.

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation, joint pain, and destruction of the synovial membranes [1]. Life expectancy of these patients can be reduced by an average of 3 to 18 years and 80% are disabled after 20 years [2, 3]. Metabolic alterations in RA due mainly to the liberation of tumor necrosis factor alpha and interleukin-1 beta can lead to rheumatoid cachexia, which is defined as “the involuntary loss of fat free mass (FFM) with minimal or not weight loss and increase or not of fat mass (FM)” which causes muscular weakness and loss of functional capacity. Also, the mean loss of FFM, present in almost two thirds of patients with RA, is between 13 and 15%. [4]. In clinical nutrition practice, a widely-employed tool used to evaluate body mass and hence nutritional status is the body mass index (BMI). However, its main  limitation is that is not able to identify rheumatoid cachexia alterations such as loss of FFM and gain of FM [5]. Several imaging techniques have been used to analyze body composition in RA patients. Currently, the most useful tool for measuring soft tissue mass and bone mineral density is dual X-ray absorptiometry (DXA) [6, 7]. Nevertheless, DXA is not always accessible and is sensitive to the patient’s hydration status [8] and also is associated with radiation exposure [9]. Therefore, a simple tool for identifying body composition alterations as rheumatoid cachexia in outpatient settings is necessary [10].

ABSTRACT

This article demonstrates a two-step method to 3D print double network hydrogels at room temperature with a low-cost ($300) 3D printer. A first network precursor solution was made 3D printable via extrusion from a nozzle by adding a layered silicate to make it shear-thinning. After printing and UVcuring, objects were soaked in a second network precursor solution and UV-cured again to create interpenetrating networks of poly(2-acrylamido-2-methylpropanesulfonate) and polyacrylamide. By varying the ratio of polyacrylamide to cross-linker, the trade-off between stiffness and maximum elongation of the gel can be tuned to yield a compression strength and elastic modulus of 61.9 and 0.44 MPa, respectively, values that are greater than those reported for bovine cartilage. The maximum compressive (93.5 MPa) and tensile (1.4 MPa) strengths of the gel are twice that of previous 3D printed gels, and the gel does not deform after it is soaked in water. By 3D printing a synthetic meniscus from an X-ray computed tomography image of an anatomical model, we demonstrate the potential to customize hydrogel implants based on 3D images of a patient’s anatomy.

INTRODUCTION

The meniscus, a network of tightly woven collagen fibers, serves as a shock absorber for the knee. A meniscal tear is among the most common knee injuries with more than 500,000 reported in the United States annually. Serious tears in the meniscus often do not heal and require surgery to repair. For the most severe tears, the entire meniscus is removed in a process known as a meniscectomy. Between 2005 and 2011, 387,000 meniscectomies were performed in the United States. If a patient who has previously lost a meniscus does begin to develop pain from early degeneration in the same knee compartment, he or she may be a candidate for meniscal replacement surgery. Currently, the only FDA approved synthetic meniscus replacement product is NUSurface. Though it provides mechanical support, its nonporous structure does not stimulate tissue regeneration, which could lead to failure over time due to wear, fatigue, or an adverse body response. Two other meniscal replacement solutions that have undergone clinical trials, CMI and Actifit, do have the ability to stimulate tissue regeneration due to their porous nature, but this tissue is not the fibrocartilage that makes up the meniscus. In addition, CMI and Actifit do not have the strength to serve as a total meniscus replacement and therefore have only been used as partial replacements in patients with some meniscus tissue remaining.

Abstract

The aims of this paper are: (1) to review the current state of the art in the field of cartilage substitution and regeneration; (2) to examine the patented biomaterials being used in preclinical and clinical stages; (3) to explore the potential of polymeric hydrogels for these applications and the reasons that hinder their clinical success. The studies about hydrogels used as potential biomaterials selected for this review are divided into the two major trends in tissue engineering: (1) the use of cell-free biomaterials; and (2) the use of cell seeded biomaterials. Preparation techniques and resulting hydrogel properties are also reviewed. More recent proposals, based on the combination of different polymers and the hybridization process to improve the properties of these materials, are also reviewed. The combination of elements such as scaffolds (cellular solids), matrices (hydrogel-based), growth factors and mechanical stimuli is needed to optimize properties of the required materials in order to facilitate tissue formation, cartilage regeneration and final clinical application. Polymer combinations and hybrids are the most promising materials for this application. Hybrid scaffolds may maximize cell growth and local tissue integration by forming cartilage-like tissue with biomimetic features.

Introduction: Current Clinical Approaches and the Need for New Developments

The aim of this paper is to review the current state of the art of materials for cartilage substitution and regeneration. Section 1 describes the current state of the art in clinical treatments. Polymeric hydrogels used in cartilage regeneration and the reasons hindering their clinical success are reviewed in Section 2. The preparation techniques using polysaccharides and the resulting hydrogel properties are described in Section 3. Finally, future trends are explored in Section 4. Several reviews about hydrogels for cartilage regeneration have been published for the last 10 years, focusing on preparation and characterization, natural and synthetic polymer precursors, gelation kinetics, cell and drug delivery, growth factors, mechanical properties and biocompatibility. Nevertheless, most of those reviews do not propose new alternatives to improve hydrogels properties which can fulfill the real clinical needs in terms of tissue regeneration, mechanical properties and degradation kinetics. Therefore, this paper reviews relevant literature published during 2013–2017, related to the application, fabrication, characterization, in vitro and in vivo assays of biomaterials based on hydrogels for cartilage regeneration. The studies selected are articles and reviews written in English.

This report presents a detailed update to our 2008 publication on the tissue engineering (TE) and stem cell industry. Data are reported through mid 2011 showing an almost three-fold growth in commercial sales over the past 4 years. In addition, the number of companies selling products or offering services has increased over twofold to 106, and they are generating a remarkable $3.5 billion in sales. Overall, the TE and stem cell sector is spending $3.6 billion and employing almost 14,000 employees. These data suggest the TE and stem cell industry has stabilized and is on a path pointing toward continued success.

Introduction

The tissue engineering (TE) industry has hardly traveled a smooth path toward success, experiencing a roller coaster ride over the last quarter century. The late Michael Lysaght devoted five articles analyzing this path over time, the first reported in 1995 and the last in 2008.1–5 Lysaght’s analyses outlined the emergence and hype, growth, downward trend, and rebound of the field and are eloquently summarized in Nerem’s article.6 Briefly, the TE industry began to develop in earnest in the 1990s and grew to 3300 full time employees (FTEs) working in over 70 companies at the end of 2000.1 By 2001, a number of TE products had reached the market, including Organogenesis’ Apligraf and Genzyme’s Carticel. Expectations and hype were high both in the science and TE business communities and in the news. In 1999, a Good Morning America report described TE as one of the greatest scientific accomplishments of the 20th century.7 Soon after the turn of the century, however, the industry entered a dark period. Private sector activity decreased 20% and the capital value of publicly traded TE companies fell a staggering 90 percent.4 This was in part due to a poor economy and the consequent decrease in investor interest, and also due to failed product launches and disappointing results from Food and Drug Administration (FDA) clinical trials. Incredibly, the industry had rebounded by our 2008 report and was back on track to meet the expectations set in the ’90s.3 The capital values for public TE companies increased over 10-fold compared to 2003 and products were entering FDA clinical trials, achieving FDA-approval, and in some cases becoming profitable. Today, as the data reported here indicate, the industry is on a path pointing toward continued success.

Abstract

Many different types of scaffold materials have been used for tissue engineering applications, and hydrogels form one group of materials that have been used in a wide variety of applications.

Hydrogels are hydrophilic polymer networks and they represent an important class of biomaterials in biotechnology and medicine because many hydrogels exhibit excellent biocompatibility with minimal inflammatory responses and tissue damage. Many studies have demonstrated the use of hydrogels in bone-tissue engineering applications. In this report, the summary was conducted on various kinds of polymers and different modification methods of hydrogels to enhance bone formation. The results revealed that hydrogels are applied for bone regeneration and that the modification of hydrogels with bioactive molecules or cell-based approaches resulted in significant increases in new bone formation. This suggests that the use of hydrogels with modification may offer an option for bone-tissue engineering, and further research is needed to identify the biological and physical properties of hydrogels.

Introduction

Many different types of scaffold materials have been used for tissue engineering applications, and hydrogels form one group of materials that have been used in a wide variety of applications (1). A gel is defined as a three-dimensional network swollen by a solvent, and hydrogels are hydrophilic polymer networks that may absorb from 10-20%, up to thousands of times their dry weight in water, and this property allows the cells to adhere, proliferate, and differentiate onto the hydrogels (2).

Hydrogels represent an important class of biomaterials in biotechnology and medicine because many of them exhibit excellent biocompatibility with minimal inflammatory responses and tissue damage, and thus many studies on bone-tissue engineering applications have been undertaken (3-6). In this report, the summary was conducted on various kinds of polymers and different modification methods of hydrogels in bone regeneration applications.