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The COVID-19 pandemic has already reaped thousands of lives, although many scientific studies already showed the possibility of this scenario. Currently, further attention is provided to patients depicting comorbidities such as respiratory or immunocompromised diseases, hypertension, and diabetes, as these individuals show a worse prognosis. Cell therapies using stem cells and/or defense cells, combined or not with traditional treatment, could be an outstanding strategy for COVID-19 management since these treatments can act by modulating the immune system, reducing proliferation, and favoring the complete elimination of the virus. In this review, we highlight the main molecular characteristics of this novel coronavirus, as well as the main pathognomonic signs of COVID-19. Furthermore, possible cell therapies are pointed out to show alternative treatments against COVID-19 and its sequels.

Resorbable synthetic and natural polymer-based membranes have been extensively studied for guided tissue regeneration. Alloplastic biomaterials are often used for tissue regeneration due to their lower immunoreactivity when compared with allogeneic and xenogeneic materials. Plenum® Guide is a synthetic membrane material based on polydioxanone (PDO), whose surface morphology closely mimics the extracellular matrix. In this study, Plenum® Guide was compared with collagen membranes as a barrier material for bone-tissue regeneration in terms of acute and subchronic systemic toxicity. Moreover, characterizations such as morphology, thermal analysis (Tm = 107.35 °C and crystallinity degree = 52.86 ± 2.97 %, final product), swelling (thickness: 0.25 mm ≅ 436% and 0.5 mm ≅ 425% within 24 h), and mechanical tests (E = 30.1 ± 6.25 MPa, σ = 3.92 ± 0.28 MPa, ε = 287.96 ± 34.68%, final product) were performed. The in vivo results revealed that the PDO membranes induced a slightly higher quantity of newly formed bone tissue than the control group (score: treated group = 15, control group = 13) without detectable systemic toxicity (clinical signs and evaluation of the membranes after necropsy did not result in differences between groups, i.e., non-reaction -&gt, tissue-reaction index = 1.3), showing that these synthetic membranes have the essential characteristics for an effective tissue regeneration. Human adipose-derived stem cells (hASCs) were seeded on PDO membranes, results demonstrated efficient cell migration, adhesion, spread, and proliferation, such that there was a slightly better hASC osteogenic differentiation on PDO than on collagen membranes. Hence, Plenum® Guide membranes are a safe and efficient alternative for resorbable membranes for tissue regeneration.

Mesenchymal stem cells (MSCs) have been isolated from a variety of tissues using different methods. Active research have confirmed that the most accessible site to collect them is the adipose tissue; which has a significantly higher concentration of MSCs. Moreover; harvesting from adipose tissue is less invasive; there are no ethical limitations and a lower risk of severe complications. These adipose-derived stem cells (ASCs) are also able to increase at higher rates and showing telomerase activity, which acts by maintaining the DNA stability during cell divisions. Adipose-derived stem cells secret molecules that show important function in other cells vitality and mechanisms associated with the immune system, central nervous system, the heart and several muscles. They release cytokines involved in pro/anti-inflammatory, angiogenic and hematopoietic processes. Adipose-derived stem cells also have immunosuppressive properties and have been reported to be “immune privileged” since they show negative or low expression of human leukocyte antigens. Translational medicine and basic research projects can take advantage of bioprinting. This technology allows precise control for both scaffolds and cells. The properties of cell adhesion, migration, maturation, proliferation, mimicry of cell microenvironment, and differentiation should be promoted by the printed biomaterial used in tissue engineering. Self-renewal and potency are presented by MSCs, which implies in an open-source for 3D bioprinting and regenerative medicine. Considering these features and necessities, ASCs can be applied in the designing of tissue engineering products. Understanding the heterogeneity of ASCs and optimizing their properties can contribute to making the best therapeutic use of these cells and opening new paths to make tissue engineering even more useful.

Innumerous protocols, using the mouse embryonic stem (ES) cells as model for in vitro study of neurons functional properties and features, have been developed. Most of these protocols are short lasting, which, therefore, does not allow a careful analysis of the neurons maturation, aging, and death processes. We describe here a novel and efficient long-lasting protocol for in vitro ES cells differentiation into neuronal cells. It consists of obtaining embryoid bodies, followed by induction of neuronal differentiation with retinoic acid of nonadherent embryoid bodies (three-dimensional model), which further allows their adherence and formation of adherent neurospheres (AN, bi-dimensional model). The AN can be maintained for at least 12 weeks in culture under repetitive mechanical splitting, providing a constant microenvironment (in vitro niche) for the neuronal progenitor cells avoiding mechanical dissociation of AN. The expression of neuron-specific proteins, such as nestin, sox1, beta III-tubulin, microtubule-associated protein 2, neurofilament medium protein, Tau, neuronal nuclei marker, gamma-aminobutyric acid, and 5-hydroxytryptamine, were confirmed in these cells maintained during 3 months under several splitting. Additionally, expression pattern of microtubule-associated proteins, such as lissencephaly (Lis1) and nuclear distribution element-like (Ndel1), which were shown to be essential for differentiation and migration of neurons during embryogenesis, was also studied. As expected, both proteins were expressed in undifferentiated ES cells, AN, and nonrosette neurons, although presenting different spatial distribution in AN. In contrast to previous studies, using cultured neuronal cells derived from embryonic and adult tissues, only Ndel1 expression was observed in the centrosome region of early neuroblasts from AN. Mature neurons, obtained from ES cells in this work, display ionic channels and oscillations of membrane electrical potential typical of electrically excitable cells, which is a characteristic feature of the functional central nervous system (CNS) neurons. Taken together, our study demonstrated that AN are a long-term culture of neuronal cells that can be used to analyze the process of neuronal differentiation dynamics. Thus, the protocol described here provides a new experimental model for studying neurological diseases associated with neuronal differentiation during early development, as well as it represents a novel source of functional cells that can be used as tools for testing the effects of toxins and/or drugs on neuronal cells.

In early embryo development, the tooth tissues are originated from the neural crest anatomical site. Neural crest stem cells are considered embryonic-like stem cells, which are maintained under the control of Hox genes. Moreover, they are clonogenic cells and are able to differentiate into various cell types, such as odontoblasts, osteoblasts, chondrocytes, neurons, melanocytes, and the muscles. Following the migration of neural crest stem cells during fetal development, the oral epithelium- and cranial crest-derived mesenchymal cells arise, which next form the dental follicle and dental pulp.

During early development, human dental pulp is originated from neural crest, which is a transient embryonic structure (Fig. 1). According to current knowledge, neural crest stem cells (NCSCs) have the capacity to self-renewal and display a developmental potential almost the same as embryonic stem (ES) cells (Kerkis and Caplan, 2012). These postmigratory NCSCs generate all craniofacial bones, the majority of the peripheral nervous system cells and tissues, as well as several non-neural cell types, such as smooth muscle cells of the cardiovascular system, pigment cells in the skin, cartilage, connective tissue, corneal epithelium and dental pulp among them. Although postmigratory, postnatal NCSCs are of restricted developmental potential they maintain functional characteristics resembling their embryonic counterparts and an ability to differentiate into a broad spectrum of cell types (Le Douarin et al., 2004, 2007, 2008; Dupin et al., 2007; Le Douarin & Dupin, 2003, 2012).

Irina Kerkis1, Mirian A. F. Hayashi2, Nelson F. Lizier1, Antonio C. Cassola3, Lygia V. Pereira4 and Alexandre Kerkis5 1Laboratory of Genetics, Butantan Institute and Department of Morphology and Genetics, Federal University of Sao Paulo, 2Departament of Pharmacology, Federal University of Sao Paulo, 3Department of Physiology and Biophysics, University of Sao Paulo, 4Institute of Biosciences, University of Sao Paulo, 5Celltrovet (Genetica Aplicada), Ltda. Brazil

During fetal development, mesenchymal progenitor (MP) cells are co-localized in major hematopoietic territories, such as yolk sac (YS), bone marrow (BM), liver (LV), and others. Studies using mouse and human MP cells isolated from fetus have shown that these cells are very similar but not identical to adult mesenchymal stem cells (MSC). Their differentiation potential is usually restricted to production of highly committed osteogenic and chondrogenic precursors. Such properties of fetal MP cells can be very useful for tissue regeneration, when a great number of committed precursors are required. The objectives of this study were to isolate and characterize MP cells from canine YS, BM, and LV in early and late stages of fetal development. Gestational stage was identified, and cell culture conditions were evaluated for efficient isolation of canine MP cells. All canine fetal MP cells expressed vimentin, nestin, and CD44 proteins. Cytokeratin 18 expression was observed in BM- and LV-MP cells, and vascular endothelial (VE)-cadherin expression was observed only in YS-MP cells. A small number of MP cells (5%) from LV and YS expressed Oct3/4 protein. The differentiation potential of canine fetal MP cells varied significantly: YS- and BM-MP cells differentiated into bone and cartilage, whereas LV-MP cells differentiation was limited to osteogenic fate. None of the canine fetal MP cells were able to differentiate into adipose cells. Our data suggest that canine fetal MP cells are an appropriate in vitro model to study MP biology from hematopoietic territories and they are a source of committed osteogenic and chondrogenic precursors for regenerative medicine.

In mammals, the specification of GC begins during cleavage; GC first appears near the gut and further migrates to the developing gonads. The lineage of GC is called germ line. They are unique cells, which undergo cell division of two types, mitosis and meiosis, in contrast to somatic cells of mammal’s body, which only divide by mitosis. Accordingly to Fig. 2 following further differentiation GC can be transformed into mature gamete, either eggs or sperm (Adams & McLaren, 2002). There is growing evidence for effects of environmental

Induced pluripotent stem cells (iPSCs) can be created by forcing expression of certain genes in fibroblasts or other somatic cell types, reversing them to a pluripotent state similar to that of embryonic stem cells (ESC). Here, we used human immature dental pulp stem cells (hIDPSCs) as an alternative source for creating iPSC. hIDPSCs can be easily isolated from accessible tissue of young and adult patients. hIDPSCs possess a fibroblast-like morphology, retaining characteristics of adult multipotent stem cells. Reprogramming of hIDPSCs was fast, producing primary hIDPSC-iPSC colonies even under feeder-free conditions. hIDPSCs acquired ESC-like morphology, expressed pluripotent markers, possessed stable, normal karyotypes, and demonstrated the ability to differentiated in vitro and in vivo. Our data demonstrate that hIDPSCs-iPSCs offer an advantageous cell system for future cell therapy and basic studies, particularly as a model for pediatric developmental disorders.

Objectives: Limbal stem cells (LSC) are self-renewing, highly proliferative cells in vitro, which express a set of specific markers and in vivo have the capacity to reconstruct the entire corneal epithelium in cases of ocular surface injury. Currently, LSC transplantation is a commonly used procedure in patients with either uni- or bilateral total limbal stem cells deficiency (TLSCD). Although LSC transplantation holds great promise for patients, several problems need to be overcome. In order to find an alternative source of cells that can partially substitute LSC in cornea epithelium reconstruction, we aimed at investigating whether human immature dental pulp stem cells (hIDPSC) would present similar key characteristics as LSC and whether they could be used for corneal surface reconstruction in a rabbit TLSCD model. Materials: We used hIDPSC, which co-express mesenchymal and embryonic stem cell markers and present the capacity to differentiate into derivative cells of the three germinal layers. TLSCD was induced by chemical burn in one eye of rabbits. After 30 days, the opaque tissue formed was removed by superficial keratectomy. Experimental group received undifferentiated hIDPSC, while control group only received amniotic membrane (AM). Both groups were sacrificed after 3 months. Results and conclusions: We have demonstrated, using immunohistochemistry and reverse transcription–polymerase chain reaction, that hIDPSCs express markers in common with LSC, such as ABCG2, integrin β1, vimentin, p63, connexin 43 and cytokeratins 3/12. They were also capable of reconstructing the eye surface after induction of unilateral TLSCD in rabbits, as shown by morphological and immunohistochemical analysis using human-specific antibodies against limbal and corneal epithelium. Our data suggest that hIDPSCs share similar characteristics with LSC and might be used as a potential alternative source of cells for corneal reconstruction.

Made available in DSpace on 2013-08-28T14:12:40Z (GMT). No. of bitstreams: 1 WOS000305892100123.pdf: 1025211 bytes, checksum: f3114ad3d761d448ea4009979a8c8d68 (MD5) Made available in DSpace on 2013-09-30T18:31:32Z (GMT). No. of bitstreams: 2 WOS000305892100123.pdf: 1025211 bytes, checksum: f3114ad3d761d448ea4009979a8c8d68 (MD5) WOS000305892100123.pdf.txt: 56945 bytes, checksum: e71c3f4e9d87411582be429d4ea1669f (MD5) Previous issue date: 2012-06-29 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:44:59Z No. of bitstreams: 2 WOS000305892100123.pdf: 1025211 bytes, checksum: f3114ad3d761d448ea4009979a8c8d68 (MD5) WOS000305892100123.pdf.txt: 56945 bytes, checksum: e71c3f4e9d87411582be429d4ea1669f (MD5) Made available in DSpace on 2014-05-20T13:44:59Z (GMT). No. of bitstreams: 2 WOS000305892100123.pdf: 1025211 bytes, checksum: f3114ad3d761d448ea4009979a8c8d68 (MD5) WOS000305892100123.pdf.txt: 56945 bytes, checksum: e71c3f4e9d87411582be429d4ea1669f (MD5) Previous issue date: 2012-06-29 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Dental pulp (DP) can be extracted from child's primary teeth (deciduous), whose loss occurs spontaneously by about 5 to 12 years. Thus, DP presents an easy accessible source of stem cells without ethical concerns. Substantial quantities of stem cells of an excellent quality and at early (2-5) passages are necessary for clinical use, which currently is a problem for use of adult stem cells. Herein, DPs were cultured generating stem cells at least during six months through multiple mechanical transfers into a new culture dish every 3-4 days. We compared stem cells isolated from the same DP before (early population, EP) and six months after several mechanical transfers (late population, LP). No changes, in both EP and LP, were observed in morphology, expression of stem cells markers (nestin, vimentin, fibronectin, SH2, SH3 and Oct3/4), chondrogenic and myogenic differentiation potential, even after cryopreservation. Six hours after DP extraction and in vitro plating, rare 5-bromo-2'-deoxyuridine (BrdU) positive cells were observed in pulp central part. After 72 hours, BrdU positive cells increased in number and were found in DP periphery, thus originating a multicellular population of stem cells of high purity. Multiple stem cell niches were identified in different zones of DP, because abundant expression of nestin, vimentin and Oct3/4 proteins was observed, while STRO-1 protein localization was restricted to perivascular niche. Our finding is of importance for the future of stem cell therapies, providing scaling-up of stem cells at early passages with minimum risk of losing their stemness. Instituto Butantan, Genet Lab, São Paulo, Brazil Fed Univ São Paulo UNIFESP, Dept Morphol, São Paulo, Brazil State Univ São Paulo UNESP, Dept Orthodont & Pediat Dent, Araraquara, SP, Brazil Case Western Reserve Univ, Dept Biol, Skeletal Res Ctr, Cleveland, OH 44106 USA State Univ São Paulo UNESP, Dept Orthodont & Pediat Dent, Araraquara, SP, Brazil FAPESP: 10/51051-6