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El impacto de la pandemia del virus SARS-CoV-2 ha generado un cambio en la atención médica de diversas enfermedades en muchos centros de salud. Los errores innatos del metabolismo (EIM) constituyen enfermedades genéticas que implican un compromiso crónico, con necesidad de seguimientos continuos y aplicación de tratamientos de alta complejidad. Además, se ha sugerido que estas patologías podrían constituir un factor de riesgo para el desarrollo de complicaciones ante la infección por SARS-CoV-2. Con el propósito de identificar cómo la pandemia ha afectado a la población con EIM, se analizaron 17 artículos en donde se evidencian los efectos que ha generado este virus en la salud, el tratamiento, la atención médica y el estilo de vida de pacientes con EIM. Los resultados aportan una visión del conocimiento de la situación de este grupo de pacientes observando que, contrario a lo esperado, hay una perspectiva positiva en términos del comportamiento de las enfermedades en poblaciones con EIM, aunque se evidenciaron algunos inconvenientes en la atención médica. Se resalta la importancia de analizar y divulgar la evidencia disponible para aportar información que contribuya al mejoramiento de la atención y asesoría de pacientes atendiendo a realidades y necesidades específicas.

The umbilical cord suspends the fetus within the amniotic cavity, where fetal dynamics is one of its many functions. Hence, the umbilical cord is a viable index in determining fetal activity. Fetal movements result in mechanical loads that are fundamental for fetal growth. At present, mechanical environment during early human fetal development is still largely unknown. To determine early fetal movement dynamics at given physiological (0.060 m) and pathological umbilical cord lengths (0.030 m, 0.020 m, 0.017 m and 0.014 m) a 2D computational model was created to simulate dynamic movement conditions. Main findings of this computational model revealed the shortest umbilical cord length (0.014 m) with a

Lysosomal storage diseases (LSDs) are a group of about 50 inborn errors of metabolism characterized by the lysosomal accumulation of partially or non-degraded molecules due to mutations in proteins involved in the degradation of macromolecules, transport, lysosomal biogenesis or modulators of lysosomal environment. Significant advances have been achieved in the diagnosis, management, and treatment of LSDs patients. In terms of approved therapies, these include enzyme replacement therapy (ERT), substrate reduction therapy, hematopoietic stem cell transplantation, and pharmacological chaperone therapy. In this review, we summarize the Colombian experience in LSDs thorough the evidence published. We identified 113 articles published between 1995 and 2019 that included Colombian researchers or physicians, and which were mainly focused in Mucopolysaccharidoses, Pompe disease, Gaucher disease, Fabry disease, and Tay-Sachs and Sandhoff diseases. Most of these articles focused on basic research, clinical cases, and mutation reports. Noteworthy, implementation of the enzyme assay in dried blood samples, led to a 5-fold increase in the identification of LSD patients, suggesting that these disorders still remain undiagnosed in the country. We consider that the information presented in this review will contribute to the knowledge of a broad spectrum of LSDs in Colombia and will also contribute to the development of public policies and the identification of research opportunities., Genetics; Metabolite; Pharmaceutical Science; Biochemistry; Epidemiology; Clinical Genetics; Laboratory Medicine; Clinical Research; Lysosomal storage diseases; Colombia; Fabry; Gaucher; mucopolysaccharidoses

In mammals, long bones are formed by ossification of a cartilaginous mould during early stages of development, through the formation of structures called the primary ossification centre, the secondary ossification centres (SOCs) and the physeal cartilages (PCs). The PC is responsible for long bone growth. The morphology of the PC and the SOCs varies during different stages of femoral growth. In this respect, several details involving the process of murine femoral development are lacking. In the present study, a morphological characterization of femur development from the embryonic period to adulthood in mice was studied using micro-computed tomography (micro-CT). To achieve this aim, femora were collected at embryonic day (E) 14.5, E16.5 and E18.5 and at postnatal day (P)1, P7, P14, P35, P46 and P52. CT images were obtained using a micro-CT scanner (X-SkyScan 1172; Micro Photonics) and analysed using the micro-CT 3D visualization software Mimics (Materialise NV, Leuven, Belgium) and NRecon (Micro Photonics). The results of the present study revealed that the femur and its PCs and SOCs undergo morphological changes during different stages of development, including changes in their shape as well as position and thickness. These changes may be due to the response of the femur to mechanical loads imposed by muscle surrounding the bone during these stages of development. The result of the present study is important to improve our knowledge related to ossification and growth patterns of mouse femur during development.

[EN] The growth plate is a cartilaginous layer present from the gestation period until the end of puberty where it ossifies joining diaphysis and epiphysis. During this period several endocrine, autocrine, and paracrine processes within the growth plate are carried out by chondrocytes; therefore, a disruption in cellular functions may lead to pathologies affecting bone development. It is known that electric fields impact the growth plate; however, parameters such as stimulation time and electric field intensity are not well documented. Accordingly, this study presents a histomorphometrical framework to assess the effect of electric fields on chondroepiphysis ex-plants. Bones were stimulated with 3.5 and 7 mV/cm, and for each electric field two exposure times were tested for 30 days (30 min and 1 h). Results evidenced that electric fields increased the hypertrophic zones compared with controls. In addition, a stimulation of 3.5 mV/cm applied for 1 h preserved the columnar cell density and its orientation. Moreover, a pre-hypertrophy differentiation in the center of the chondroepiphysis was observed when explants were stimulated during 1 h with both electric fields. These findings allow the understanding of the effect of electrical stimulation over growth plate organization and how the stimulation modifies chondrocytes morphophysiology., This research was supported by COLCIENCIAS Administrative Department of Science, Technology and Innovation. The authors gratefully thank the research support from the Biotechnology Institute of the Universidad Nacional de Colombia, for providing the lab space at the Biomimetics Laboratory and the reactants to perform the experimental approach of this study. Research reported in this publication was supported by COLCIENCIAS Administrative Department of Science, Technology and Innovation (Announcement 712-2015 Grant No 50457).

Magnetic fields (MFs) have been used as an external stimulus to increase cell proliferation in chondrocytes and extracellular matrix (ECM) synthesis of articular cartilage. However, previously published studies have not shown that MFs are homogeneous through cell culture systems. In addition, variables such as stimulation times and MF intensities have not been standardized to obtain the best cellular proliferative rate or an increase in molecular synthesis of ECM. In this work, a stimulation device, which produces homogeneous MFs to stimulate cell culture surfaces was designed and manufactured using a computational model. Furthermore, an in vitro culture of primary rat chondrocytes was established and stimulated with two MF schemes to measure both proliferation and ECM synthesis. The best proliferation rate was obtained with an MF of 2 mT applied for 3 h, every 6 h for 8 days. In addition, the increase in the synthesis of glycosaminoglycans was statistically significant when cells were stimulated with an MF of 2 mT applied for 5 h, every 6 h for 8 days. These findings suggest that a stimulation with MFs is a promising tool that could be used to improve in vitro treatments such as autologous chondrocyte implantation, either to increase cell proliferation or stimulate molecular synthesis. Bioelectromagnetics. 2020;41:41-51 © 2019 Bioelectromagnetics Society.

The use of specialized centers has been the main alternative for an appropriate diagnosis, management and follow up of patients affected by inborn errors of metabolism (IEM). These centers facilitate the training of different professionals, as well as the research at basic, translational and clinical levels. Nevertheless, few reports have described the experience of these centers and their local and/or global impact in the study of IEM. In this paper, we describe the experience of a Colombian reference center for the research, diagnosis, training and education on IEM. During the last 20 years, important advances have been achieved in the clinical knowledge of these disorders, as well as in the local availability of several diagnosis tests. Organic acidurias have been the most frequently detected diseases, followed by aminoacidopathies and peroxisomal disorders. Research efforts have been focused in the production of recombinant proteins in microorganisms towards the development of new enzyme replacement therapies, the design of gene therapy vectors and the use of bioinformatics tools for the understanding of IEM. In addition, this center has participated in the education and training of a large number professionals at different levels, which has contributed to increase the knowledge and divulgation of these disorders along the country. Noteworthy, in close collaboration with patient advocacy groups, we have participated in the discussion and construction of initiatives for the inclusion of diagnosis tests and treatments in the health system.

Electric fields (EFs) have been used as external biophysical stimuli to increase cell population and stimulate the molecular synthesis of chondrocytes. However, in the methodology reported by different researchers there is no evidence about the procedure to calculate EFs. This work presents a new framework to calculate EFs and modulate proliferation, cell death and glycosaminoglycan synthesis. For this study, we used a computational analysis, by a finite elements method for experimental setting, to find the dielectric constants of the cell culture medium and the experimental geometrical configuration. Chondrocytes were stimulated with EFs of 4 and 8 mV/cm, and for each of these EFs, three exposure times were tested (30 min, 1 and 5 h). We observed an increment in cell population when an electric field of 4 mV/cm was applied during 30 min. The glycosaminoglycan synthesis remained stable after an electric field of 8 mV/cm was applied during 5 h. No changes in cell population and molecular synthesis were perceived when EFs were applied during 1 h. This approach is a promising tool that could be used to enhance in vitro procedures in order to obtain well-characterized chondrocyte cell cultures either by increasing cell proliferation or stimulating molecular synthesis.

ObjectiveHyaline cartilage degenerative pathologies induce morphologic and biomechanical changes resulting in cartilage tissue damage. In pursuit of therapeutic options, electrical and mechanical stimulation have been proposed for improving tissue engineering approaches for cartilage repair. The purpose of this review was to highlight the effect of electrical stimulation and mechanical stimuli in chondrocyte behavior.DesignDifferent information sources and the MEDLINE database were systematically revised to summarize the different contributions for the past 40 years.ResultsIt has been shown that electric stimulation may increase cell proliferation and stimulate the synthesis of molecules associated with the extracellular matrix of the articular cartilage, such as collagen type II, aggrecan and glycosaminoglycans, while mechanical loads trigger anabolic and catabolic responses in chondrocytes.ConclusionThe biophysical stimuli can increase cell proliferation and stimulate molecules associated with hyaline cartilage extracellular matrix maintenance.

Long bone formation starts early during embryonic development through a process known as endochondral ossification. This is a highly regulated mechanism that involves several mechanical and biochemical factors. Because long bone development is an extremely complex process, it is unclear how biochemical regulation is affected when dynamic loads are applied, and also how the combination of mechanical and biochemical factors affect the shape acquired by the bone during early development. In this study, we develop a mechanobiological model combining: (1) a reaction–diffusion system to describe the biochemical process and (2) a poroelastic model to determine the stresses and fluid flow due to loading. We simulate endochondral ossification and the change in long bone shapes during embryonic stages. The mathematical model is based on a multiscale framework, which consisted in computing the evolution of the negative feedback loop between Ihh/PTHrP and the diffusion of VEGF molecule (on the order of days) and dynamic loading (on the order of seconds). We compare our morphological predictions with the femurs of embryonic mice. The results obtained from the model demonstrate that pattern formation of Ihh, PTHrP and VEGF predict the development of the main structures within long bones such as the primary ossification center, the bone collar, the growth fronts and the cartilaginous epiphysis. Additionally, our results suggest high load pressures and frequencies alter biochemical diffusion and cartilage formation. Our model incorporates the biochemical and mechanical stimuli and their interaction that influence endochondral ossification during embryonic growth. The mechanobiochemical framework allows us to probe the effects of molecular events and mechanical loading on development of bone.

Tyrosinemia type I is an inborn error of metabolism of the amino acids, caused by a deficiency or absence of the enzyme activity of fumaril-acetoacetate hydrolase in the catabolism of tyrosine. It has a variable clinical presentation, from an acute severe neonatal form until a virtually asymptomatic form with late presentation. The rapid diagnosis and nutritional management is essential for a good outcome.Four clinical cases are presented, two of which were confirmed as tyrosinemia type I and two that were initially misdiagnosed. Diagnostic criteria and therapeutic management are emphasized.

During skeleton formation, mesenchymal cells condense and differentiate into chondrocytes in a process known as chondrogenesis. Glycosaminoglycans (GAGs), main components of aggrecan in the extracellular matrix (ECM), have an important role in this process. An in vitro simplified system has been devised to study chondrogenesis using mesenchymal progenitor cells. Although the capacity of mesenchymal stromal cells to differentiate into the chondrogenic lineage is well established, there is a lack of knowledge with respect to lysosomal enzyme activity during the chondrogenic process. To further understand GAG's catabolic activities during in vitro chondrogenesis, we evaluated three lysosomal enzymes. Chondrogenic differentiation was demonstrated by Alcian blue positive stain quantified by a grading system using ImageJ. Enzyme activity for N-acetylgalactosamine-6-sulfate-sulfatase during chondrogenic induction decreased significantly with time of culture; β-galactosidase enzyme activity had a similar tendency...

Iduronate-2-sulfate sulfatase (IDS; EC 3.1.6.13) is an enzyme that belongs to human sulfatases. IDS deficiency causes the Hunter syndrome or mucopolysaccharidosis type II (MPS II; OMIM 309900). We have been developing an expression system for human recombinant IDS (hrIDS) in Pichia pastoris , therefore a method was required for its detection during production and purification processes, which could be used also to measure the enzyme in human fluids. In this study, an immunoquantification assay for human and recombinant IDS was developed with the combination of two antibodies. Rabbit IgG and chicken IgY were used as IDS capture and detection antibodies, respectively. Chicken IgY antibodies were developed against specific amino acid sequences present in IDS but absent in other human sulfatases. hrIDS produced in P. pastoris , commercial hrIDS, and normal human plasma samples were used as antigens and immunoquantification results were compared to enzyme activity. The technique was linear over the range 8 to 500 ng mL −1 using commercial hrIDS. The concentration range detected for IDS in normal human plasma was 14.43 to 287.88 ng mL −1 . The hrIDS was detected in P. pastoris cultures even when the enzyme was inactive, which is convenient for monitoring the production of recombinant proteins. These results show that chicken site-specific antibodies provide a good alternative, as a substitute of monoclonal antibodies, for the detection of human proteins. This is the first report on the development of an ELISA system to detect and quantify IDS with IgY antibodies.

Background We previously demonstrated the therapeutic benefits of pentosan polysulfate (PPS) in a rat model of mucopolysaccharidosis (MPS) type VI. Reduction of inflammation, reduction of glycosaminoglycan (GAG) storage, and improvement in the skeletal phenotype were shown. Herein, we evaluate the long-term safety and therapeutic effects of PPS in a large animal model of a different MPS type, MPS I dogs. We focused on the arterial phenotype since this is one of the most consistent and clinically significant features of the model. Methodology/Principal Findings MPS I dogs were treated with daily oral or biweekly subcutaneous (subQ) PPS at a human equivalent dose of 1.6 mg/kg for 17 and 12 months, respectively. Safety parameters were assessed at 6 months and at the end of the study. Following treatment, cytokine and GAG levels were determined in fluids and tissues. Assessments of the aorta and carotid arteries also were performed. No drug-related increases in liver enzymes, coagulation factors, or other adverse effects were observed. Significantly reduced IL-8 and TNF-alpha were found in urine and cerebrospinal fluid (CSF). GAG reduction was observed in urine and tissues. Increases in the luminal openings and reduction of the intimal media thickening occurred in the carotids and aortas of PPS-treated animals, along with a reduction of storage vacuoles. These results were correlated with a reduction of GAG storage, reduction of clusterin 1 staining, and improved elastin integrity. No significant changes in the spines of the treated animals were observed. Conclusions PPS treatment led to reductions of pro-inflammatory cytokines and GAG storage in urine and tissues of MPS I dogs, which were most evident after subQ administration. SubQ administration also led to significant cytokine reductions in the CSF. Both treatment groups exhibited markedly reduced carotid and aortic inflammation, increased vessel integrity, and improved histopathology. We conclude that PPS may be a safe and useful therapy for MPS I, either as an adjunct or as a stand-alone treatment that reduces inflammation and GAG storage.

Summary Objective The overall aim of this study was to evaluate how supplementation of chondrocyte media with recombinant acid ceramidase (rhAC) influenced cartilage repair in a rat osteochondral defect model. Methods Primary chondrocytes were grown as monolayers in polystyrene culture dishes with and without rhAC (added once at the time of cell plating) for 7 days, and then seeded onto Bio-Gide ® collagen scaffolds and grown for an additional 3 days. The scaffolds were then introduced into osteochondral defects created in Sprague–Dawley rat trochlea by a microdrilling procedure. Analysis was performed 6 weeks post-surgery macroscopically, by micro-CT, histologically, and by immunohistochemistry. Results Treatment with rhAC led to increased cell numbers and glycosaminoglycan (GAG) production (∼2 and 3-fold, respectively) following 7 days of expansion in vitro . Gene expression of collagen 2, aggrecan and Sox-9 also was significantly elevated. After seeding onto Bio-Gide ® , more rhAC treated cells were evident within 4 h. At 6 weeks post-surgery, defects containing rhAC-treated cells exhibited more soft tissue formation at the articular surface, as evidenced by microCT, as well as histological evidence of enhanced cartilage repair. Notably, collagen 2 immunostaining revealed greater surface expression in animals receiving rhAC treated cells as well. Collagen 10 staining was not enhanced. Conclusion The results further demonstrate the positive effects of rhAC treatment on chondrocyte growth and phenotype in vitro , and reveal for the first time the in vivo effects of the treated cells on cartilage repair.

La acidemia metilmalónica es un desorden causado por anormalidad en la enzima metil ma- lonil CoA mutasa o su cofactor Adenosilcobalamina. Esta holoenzima se encuentra implicada en el catabolismo de varios aminoácidos entre los que se incluyen dos de cadena ramificada (isoleucina y valina). Puede presentarse como una forma severa de inicio neonatal hasta formas con síntomas lentamente progresivos como hipotonía y retardo en el desarrollo. El diagnóstico y tratamiento oportuno, pueden modificar el curso y desenlace de la enfermedad, mejorando la calidad de vida del paciente. Reportamos el caso de un lactante de 3 meses, con pancito- penia, hipotonía, retardo en desarrollo y convulsiones. Se diagnosticó acidemia metilmalónica mediante cromatografía de ácidos orgánicos en orina. El paciente fue tratado con Cianoco- balamina, restricción dietaria y levetiracetam con respuesta clínica favorable. Actualmente permanece libre de crisis, los índices de desarrollo son normales y la pancitopenia resolvió. Este caso muestra como el diagnóstico y tratamiento temprano en un paciente con acidemia metilmalónica, aun cuando se origine por déficit de cofactor, puede favorecer el pronóstico neurológico y funcional.

Growth plate characteristics affect SOC development.Mechanical environment within growth plate varies according to epiphyseal ossification state.Mechanical stimuli may affect similarly growth plate and epiphyseal ossification. Mechanical stimuli play a significant role in the process of long bone development as evidenced by clinical observations and in vivo studies. Up to now approaches to understand stimuli characteristics have been limited to the first stages of epiphyseal development. Furthermore, growth plate mechanical behavior has not been widely studied. In order to better understand mechanical influences on bone growth, we used Carter and Wong biomechanical approximation to analyze growth plate mechanical behavior, and explore stress patterns for different morphological stages of the growth plate. To the best of our knowledge this work is the first attempt to study stress distribution on growth plate during different possible stages of bone development, from gestation to adolescence. Stress distribution analysis on the epiphysis and growth plate was performed using axisymmetric (3D) finite element analysis in a simplified generic epiphyseal geometry using a linear elastic model as the first approximation. We took into account different growth plate locations, morphologies and widths, as well as different epiphyseal developmental stages. We found stress distribution during bone development established osteogenic index patterns that seem to influence locally epiphyseal structures growth and coincide with growth plate histological arrangement.

Long bone growth relies on the continuous bone formation from cartilaginous tissue (endochondral ossification). This process starts in the central region (diaphysis) of the forming bone and short before birth, ossification starts in bone extremes (epiphysis). A cartilaginous region known as the growth plate is maintained until adolescence between epiphysis and diaphysis to further contribute to longitudinal growth. Even though there are several biochemical factors controlling this process, there is evidence revealing an important regulatory role of mechanical stimuli. Up to now approaches to understand mechanical effects on ossification have been limited to epiphysis. In this work, based on Carter's mathematical model for epiphyseal ossification, we explored human growth plate response to mechanical loads. We analyzed growth plate stress distribution using finite element method for a generic bone considering different stages of bone development in order to shed light on mechanical contribution to growth plate function. Results obtained revealed that mechanical environment within the growth plate change as epiphyseal ossification progresses. Furthermore, results were compared with physiological behavior, as reported in literature, to analyze the role of mechanical stimulus over development. Our results suggest that mechanical stimuli may play different regulation roles on growth plate behavior through normal long bone development. However, as this approach only took into account mechanical aspects, failed to accurately predict biological behavior in some stages. In order to derive biologically relevant information from computational models it is necessary to consider biological contribution and possible mechanical–biochemical interactions affecting human growth plate physiology. Along these lines, we propose the dilatatorial parameter k used by Carter et al. should assume different values corresponding to the developmental stage in question. Thus, reflecting biochemical contribution changes over time.

The growth plate is a cartilaginous structure located in the metaphysis of long bones, characterized histologically by its stratification and columnar arrangement. It is responsible for assuring longitudinal growth. Evaluation of growth plate histological characteristics has been traditionally performed using qualitative observation; however, some quantitative approaches have been reported using complex techniques. Here, we propose a simple quantitative images based analysis in order to evaluate objectively columnar arrangement within growth plate. For this, we defined six descriptors that were condensated in a geometric tensor. This tensor could be used as a single parameter to evaluate the growth plate organization. Validation of the tensor was performed with growth plate microphotographs of three healthy species (rat, pig and rabbit) and an abnormal one (Csf1tl/Csf1tl rat) found in specialized literature. According to our results, the descriptors and the tensor give a complete picture of the organization of the growth plate, reflecting the expected stratification and columnar arrangement of the cells within the tissue. This methodology could be a reliable tool for evaluation of growth plate structure for research and diagnostic purposes, taking into account that it can be easily implemented.

During embryological limb formation mesenchymal cells condense and differentiate into chondrocytes, in a process known as chondrogenesis. These chondrocytes synthesize glycosaminoglycans (GAGs), thus playing an important role in this process. A simplified system in vitro chondrogenesis, using adult mesenchymal stromal cells (MSCs) has been demonstrated. This differentiation potential is usually assessed by histological staining. Objective. Establishment of a semi-automatic grading system for histochemistry stains and immunohistochemistry assays. Materials and methods. For chondrogenesis cells were cultured for three weeks in aggregates with inducing media. Total GAGs were measured using dimethylmethylene blue (DMB) method. For histological analyses aggregates were stained with Alcian blue for total GAGs detection and immunohistochemistry (IHC) for aggrecan was performed. Semi-automatic grading for all slides was obtained after ImageJ analysis. Results. MSCs cultured as aggregates in chondrogenic differentiation media had similar protein concentrations for all time points, suggesting cellularity remained homogenous during culture. Total GAGs was higher for aggregates cultured in chondrogenic compared to complete media. The same trend was observed for Alcian blue stain grades by blinded observer and analysis using ImageJ software. Aggrecan’s IHC analysis had a decreasing tendency with time for aggregates in chondrogenic media for blinded observer and ImageJ evaluation. Conclusion. We developed a functional system for semi-automatic slide grading. We corroborated these results by biochemical analysis with comparable results. To our knowledge, for in vitro chondrogenesis, this is the first report to evaluate stains usingthis methodology. This procedure might be useful for other applications in the field of Biology and Medical Sciences.Key words: mesenchymal stromal cells, in vitro chondrogenesis, glycosaminoglycans, ImageJ

Introducción. El trasplante es una opción terapéutica en la cardiomiopatía chagásica. Para la detección temprana de una posible reactivación de la infección, se propone el uso de pruebas de reacción en cadena de la polimerasa (PCR) a partir de biopsias endomiocárdicas; el modelo de ratón es una aproximación preliminar para evaluar la aplicación de éstas. Objetivo. Evaluar la aplicación de las pruebas de PCR basadas en los iniciadores TcH2AF-R y S35-S36 para la detección de T. cruzi en tejido cardiaco de ratones infectados con el parásito. Materiales y métodos. Se infectaron por vía intraperitoneal dos grupos de ratones ICR de 15 y 10 individuos con 0,3 ml de PBS que contenían 1x106 tripomastigotes de la cepa MHOM/CO/ 2001/D.A. (T. cruzi I) o 1x104 tripomastigotes de la cepa MHOM/BR/00/Y (T. cruzi II), respectivamente. El seguimiento de la parasitemia se realizó mediante microhematocrito y presencia de parásitos en el corazón a los 30, 60 (modelo agudo), 100 y 150 (modelo crónico) días por medio de histopatología y de las PCR TcH2AF-R y S35-S36. Resultados. La histopatología mostró alteraciones en el miocardio y presencia de amastigotes en los modelos agudo y crónico. En contraste al microhematocrito y al análisis histopatológico, la PCR S35-S36 permitió la detección de ambas cepas del parásito. La PCR TcH2AF-R detectó la cepa T. cruzi I con un desempeño superior al microhematocrito y al análisis histopatológico. Conclusiones. El uso de ambas pruebas de PCR puede ser útil en la confirmación de la reactivación de la infección postrasplante.