Intelligent bioprocessing for haemotopoietic cell cultures using monitoring and design of experiments

DOE-based process optimization for development of efficient methods for purification of recombinant hepatitis B surface antigen from Pichia pastoris feedstock using Capto adhere resin

Background

The multimodal chromatography resins, such as Capto adhere, are considered good candidates to be utilized in downstream processing due to their high capacity and selectivity; however, their multimodal interactions lead to an intricacy in the adsorption-desorption patterns and systematic characterization of conditions for process steps is necessary.

Methods

Capto adhere, a strong ion exchanger with multimodal functionality, was used in this study for the final aim of recombinant hepatitis B surface antigen (rHBsAg) purification from Pichia pastoris (P. pastoris) industrial feedstock. Optimization of various parameters was done using the design of experiments (DOE) approach to determine the best binding and non-binding conditions.

Results

Maximum rHBsAg binding on Capto adhere occurred in 20 mM sodium acetate, pH 4.5, and a binding capacity of about 0.75 mg/ml was achieved, which was much higher than rHBsAg binding capacity of other resins reported so far. In elution optimization investigations, it was revealed that 1 M arginine (buffered in 50 mM sodium phosphate, pH 6.5) was the most efficient eluting agent. The binding and elution optimal conditions were utilized for further purification of rHBsAg from P. pastoris industrial feedstock in bind-elute mode, and the recovery and purity of the obtained rHBsAg were about 60% and 100%, respectively. Following optimization in the flow-through purification mode, the target protein recovery was significantly increased (up to 97%) and the target protein purity of more than 95% was achievable. SEC-HPLC analysis showed that the obtained retention times for the purified rHBsAg were similar to those reported previously.

Conclusions

These results suggest that Capto adhere under such optimized conditions can be considered as a good candidate for efficient purification of rHBsAg from P. pastoris industrial feedstock in downstream processing.

Monitoring and modelling the glutamine metabolic pathway: a review and future perspectives

BACKGROUND

Analysis of the glutamine metabolic pathway has taken a special place in metabolomics research in recent years, given its important role in cell biosynthesis and bioenergetics across several disorders, especially in cancer cell survival. The science of metabolomics addresses the intricate intracellular metabolic network by exploring and understanding how cells function and respond to external or internal perturbations to identify potential therapeutic targets. However, despite recent advances in metabolomics, monitoring the kinetics of a metabolic pathway in a living cell in situ, real-time and holistically remains a significant challenge.

AIM

This review paper explores the range of analytical approaches for monitoring metabolic pathways, as well as physicochemical modeling techniques, with a focus on glutamine metabolism. We discuss the advantages and disadvantages of each method and explore the potential of label-free Raman microspectroscopy, in conjunction with kinetic modeling, to enable real-time and in situ monitoring of the cellular kinetics of the glutamine metabolic pathway.

KEY SCIENTIFIC CONCEPTS

Given its important role in cell metabolism, the ability to monitor and model the glutamine metabolic pathways are highlighted. Novel, label free approaches have the potential to revolutionise metabolic biosensing, laying the foundation for a new paradigm in metabolomics research and addressing the challenges in monitoring metabolic pathways in living cells.

Recent advances in engineering hydrogels for niche biomimicking and hematopoietic stem cell culturing

Hematopoietic stem cells (HSCs) provide a life-long supply of haemopoietic cells and are indispensable for clinical transplantation in the treatment of malignant hematological diseases. Clinical applications require vast quantities of HSCs with maintained stemness characteristics. Meeting this demand poses often insurmountable challenges for traditional culture methods. Creating a supportive artificial microenvironment for the culture of HSCs, which allows the expansion of the cells while maintaining their stemness, is becoming a new solution for the provision of these rare multipotent HSCs. Hydrogels with good biocompatibility, excellent hydrophilicity, tunable biochemical and biophysical properties have been applied in mimicking the hematopoietic niche for the efficient expansion of HSCs. This review focuses on recent progress in the use of hydrogels in this specialized application. Advanced biomimetic strategies use for the creation of an artificial haemopoietic niche are discussed, advances in combined use of hydrogel matrices and microfluidics, including the emerging organ-on-a-chip technology, are summarized. We also provide a brief description of novel stimulus-responsive hydrogels that are used to establish an intelligent dynamic cell microenvironment. Finally, current challenges and future perspectives of engineering hydrogels for HSC biomedicine are explored.

Clever Experimental Designs: Shortcuts for Better iPSC Differentiation

For practical use of pluripotent stem cells (PSCs) for disease modelling, drug screening, and regenerative medicine, the cell differentiation process needs to be properly refined to generate end products with consistent and high quality. To construct and optimize a robust cell-induction process, a myriad of cell culture conditions should be considered. In contrast to inefficient brute-force screening, statistical design of experiments (DOE) approaches, such as factorial design, orthogonal array design, response surface methodology (RSM), definitive screening design (DSD), and mixture design, enable efficient and strategic screening of conditions in smaller experimental runs through multifactorial screening and/or quantitative modeling. Although DOE has become routinely utilized in the bioengineering and pharmaceutical fields, the imminent need of more detailed cell-lineage specification, complex organoid construction, and a stable supply of qualified cell-derived material requires expedition of DOE utilization in stem cell bioprocessing. This review summarizes DOE-based cell culture optimizations of PSCs, mesenchymal stem cells (MSCs), hematopoietic stem cells (HSCs), and Chinese hamster ovary (CHO) cells, which guide effective research and development of PSC-derived materials for academic and industrial applications.

Biotechnology and Bioprocesses: Their Contribution to Sustainability

Significant advancements in biotechnology have resulted in the development of numerous fundamental bioprocesses, which have consolidated research and development and industrial progress in the field. These bioprocesses are used in medical therapies, diagnostic and immunization procedures, agriculture, food production, biofuel production, and environmental solutions (to address water-, soil-, and air-related problems), among other areas. The present study is a first approach toward the identification of scientific and technological bioprocess trajectories within the framework of sustainability. The method included a literature search (Scopus), a patent search (Patentscope), and a network analysis for the period from 2010 to 2019. Our results highlight the main technological sectors, countries, institutions, and academic publications that carry out work or publish literature related to sustainability and bioprocesses. The network analysis allowed for the identification of thematic clusters associated with sustainability and bioprocesses, revealing different related scientific topics. Our conclusions confirm that biotechnology is firmly positioned as an emerging knowledge area. Its dynamics, development, and outcomes during the study period reflect a substantial number of studies and technologies focused on the creation of knowledge aimed at improving economic development, environmental protection, and social welfare.

Leveraging advances in biology to design biomaterials

Biomaterials have dramatically increased in functionality and complexity, allowing unprecedented control over the cells that interact with them. From these engineering advances arises the prospect of improved biomaterial-based therapies, yet practical constraints favour simplicity. Tools from the biology community are enabling high-resolution and high-throughput bioassays that, if incorporated into a biomaterial design framework, could help achieve unprecedented functionality while minimizing the complexity of designs by identifying the most important material parameters and biological outputs. However, to avoid data explosions and to effectively match the information content of an assay with the goal of the experiment, material screens and bioassays must be arranged in specific ways. By borrowing methods to design experiments and workflows from the bioprocess engineering community, we outline a framework for the incorporation of next-generation bioassays into biomaterials design to effectively optimize function while minimizing complexity. This framework can inspire biomaterials designs that maximize functionality and translatability.

Microcarrier-based platforms for in vitro expansion and differentiation of human pluripotent stem cells in bioreactor culture systems

Human pluripotent stem cells (hPSC) have attracted a great attention as an unlimited source of cells for cell therapies and other in vitro biomedical applications such as drug screening, toxicology assays and disease modeling. The implementation of scalable culture platforms for the large-scale production of hPSC and their derivatives is mandatory to fulfill the requirement of obtaining large numbers of cells for these applications. Microcarrier technology has been emerging as an effective approach for the large scale ex vivo hPSC expansion and differentiation. This review presents recent achievements in hPSC microcarrier-based culture systems and discusses the crucial aspects that influence the performance of these culture platforms. Recent progress includes addressing chemically-defined culture conditions for manufacturing of hPSC and their derivatives, with the development of xeno-free media and microcarrier coatings to meet good manufacturing practice (GMP) quality requirements. Finally, examples of integrated platforms including hPSC expansion and directed differentiation to specific lineages are also presented in this review.

Hypercapnia slows down proliferation and apoptosis of human bone marrow promyeloblasts

Stem cells are being applied in increasingly diverse fields of research and therapy; as such, growing and culturing them in scalable quantities would be a huge advantage for all concerned. Gas mixtures containing 5 % CO2 are a typical concentration for the in vitro culturing of cells. The effect of varying the CO2 concentration on promyeloblast KG-1a cells was investigated in this paper. KG-1a cells are characterized by high expression of CD34 surface antigen, which is an important clinical surface marker for human hematopoietic stem cells (HSCs) transplantation. KG-1a cells were cultured in three CO2 concentrations (1, 5 and 15 %). Cells were batch-cultured and analyzed daily for viability, size, morphology, proliferation, and apoptosis using flow cytometry. No considerable differences were noted in KG-1a cell morphological properties at all three CO2 levels as they retained their myeloblast appearance. Calculated population doubling time increased with an increase in CO2 concentration. Enhanced cell proliferation was seen in cells cultured in hypercapnic conditions, in contrast to significantly decreased proliferation in hypocapnic populations. Flow cytometry analysis revealed that apoptosis was significantly (p = 0.0032) delayed in hypercapnic cultures, in parallel to accelerated apoptosis in hypocapnic ones. These results, which to the best of our knowledge are novel, suggest that elevated levels of CO2 are favored for the enhanced proliferation of bone marrow (BM) progenitor cells such as HSCs.

Proportional-Integral-Derivative (PID) Control of Secreted Factors for Blood Stem Cell Culture

Clinical use of umbilical cord blood has typically been limited by the need to expand hematopoietic stem and progenitor cells (HSPC) ex vivo. This expansion is challenging due to the accumulation of secreted signaling factors in the culture that have a negative regulatory effect on HSPC output. Strategies for global regulation of these factors through dilution have been developed, but do not accommodate the dynamic nature or inherent variability of hematopoietic cell culture. We have developed a mathematical model to simulate the impact of feedback control on in vitro hematopoiesis, and used it to design a proportional-integral-derivative (PID) control algorithm. This algorithm was implemented with a fed-batch bioreactor to regulate the concentrations of secreted factors. Controlling the concentration of a key target factor, TGF-β1, through dilution limited the negative effect it had on HSPCs, and allowed global control of other similarly-produced inhibitory endogenous factors. The PID control algorithm effectively maintained the target soluble factor at the target concentration. We show that feedback controlled dilution is predicted to be a more cost effective dilution strategy compared to other open-loop strategies, and can enhance HSPC expansion in short term culture. This study demonstrates the utility of secreted factor process control strategies to optimize stem cell culture systems, and motivates the development of multi-analyte protein sensors to automate the manufacturing of cell therapies.

Evaluation of umbilical cord blood CD34 (+) hematopoietic stem cell expansion in co-culture with bone marrow mesenchymal stem cells in the presence of TEPA

BACKGROUND

During the last three decades hematopoietic stem cells (HSC) have become a standard protocol for the treatment of many hematologic malignancies and non-malignant disorders. Umbilical cord blood (UCB), as a source of HSCs, has many advantages compared with other sources. One major drawback in using this source in treatment of adult patients is the low HSC dose available. Ex vivo expansion of HSCs is a solution to overcome this limitation. In this study we used TEPA, as a Cu chelator, and human bone marrow (BM) mesenchymal stem cells (MSCs) to investigate expansion rate of UCB-HSCs.

MATERIALS AND METHODS

CB-HSCs were isolated using miniMACS magnetic separation system. We cultured the enriched CD34(+)cells in various conditions: culture condition A, supplemented only with recombinant cytokines; culture condition B, supplemented with BM-MSCs as a cell feeder layer and recombinant cytokines; culture condition C, supplemented with recombinant cytokines and TEPA; culture condition D, supplemented with recombinant cytokines, BM-MSCs as a cell feeder layer and TEPA. In order to evaluate the HSC expansion, we performed cell count, analysis of CD34(+) expression by flow cytometry, and colony-forming cell assay on Day 10 after culture.

RESULTS

The most fold increase in CD34(+) cell, total cell, and total colony numbers was observed in culture condition D (110.11 ± 15.3, 118.5 ± 21, and 172.9 ± 44.7, respectively) compared to other conditions.

CONCLUSION

The results showed that co-culture of HSCs with BM-MSCs in the presence of copper chelating agent (TEPA) could dramatically increase expansion rate of UCB-HSCs. Therefore, this strategy could be useful for HSC expansion.

Control of scar tissue formation in the cornea: strategies in clinical and corneal tissue engineering

Corneal structure is highly organized and unified in architecture with structural and functional integration which mediates transparency and vision. Disease and injury are the second most common cause of blindness affecting over 10 million people worldwide. Ninety percent of blindness is permanent due to scarring and vascularization. Scarring caused via fibrotic cellular responses, heals the tissue, but fails to restore transparency. Controlling keratocyte activation and differentiation are key for the inhibition and prevention of fibrosis. Ophthalmic surgery techniques are continually developing to preserve and restore vision but corneal regression and scarring are often detrimental side effects and long term continuous follow up studies are lacking or discouraging. Appropriate corneal models may lead to a reduced need for corneal transplantation as presently there are insufficient numbers or suitable tissue to meet demand. Synthetic optical materials are under development for keratoprothesis although clinical use is limited due to implantation complications and high rejection rates. Tissue engineered corneas offer an alternative which more closely mimic the morphological, physiological and biomechanical properties of native corneas. However, replication of the native collagen fiber organization and retaining the phenotype of stromal cells which prevent scar-like tissue formation remains a challenge. Careful manipulation of culture environments are under investigation to determine a suitable environment that simulates native ECM organization and stimulates keratocyte migration and generation.

Tissue engineering and regenerative medicine: history, progress, and challenges

The past three decades have seen the emergence of an endeavor called tissue engineering and regenerative medicine in which scientists, engineers, and physicians apply tools from a variety of fields to construct biological substitutes that can mimic tissues for diagnostic and research purposes and can replace (or help regenerate) diseased and injured tissues. A significant portion of this effort has been translated to actual therapies, especially in the areas of skin replacement and, to a lesser extent, cartilage repair. A good amount of thoughtful work has also yielded prototypes of other tissue substitutes such as nerve conduits, blood vessels, liver, and even heart. Forward movement to clinical product, however, has been slow. Another offshoot of these efforts has been the incorporation of some new exciting technologies (e.g., microfabrication, 3D printing) that may enable future breakthroughs. In this review we highlight the modest beginnings of the field and then describe three application examples that are in various stages of development, ranging from relatively mature (skin) to ongoing proof-of-concept (cartilage) to early stage (liver). We then discuss some of the major issues that limit the development of complex tissues, some of which are fundamentals-based, whereas others stem from the needs of the end users.

Ex vivo mimicry of normal and abnormal human hematopoiesis

Hematopoietic stem cells require a unique microenvironment in order to sustain blood cell formation; the bone marrow (BM) is a complex three-dimensional (3D) tissue wherein hematopoiesis is regulated by spatially organized cellular microenvironments termed niches. The organization of the BM niches is critical for the function or dysfunction of normal or malignant BM(5). Therefore a better understanding of the in vivo microenvironment using an ex vivo mimicry would help us elucidate the molecular, cellular and microenvironmental determinants of leukemogenesis. Currently, hematopoietic cells are cultured in vitro in two-dimensional (2D) tissue culture flasks/well-plates requiring either co-culture with allogenic or xenogenic stromal cells or addition of exogenous cytokines. These conditions are artificial and differ from the in vivo microenvironment in that they lack the 3D cellular niches and expose the cells to abnormally high cytokine concentrations which can result in differentiation and loss of pluripotency. Herein, we present a novel 3D bone marrow culture system that simulates the in vivo 3D growth environment and supports multilineage hematopoiesis in the absence of exogenous growth factors. The highly porous scaffold used in this system made of polyurethane (PU), facilitates high-density cell growth across a higher specific surface area than the conventional monolayer culture in 2D. Our work has indicated that this model supported the growth of human cord blood (CB) mononuclear cells (MNC) and primary leukemic cells in the absence of exogenous cytokines. This novel 3D mimicry provides a viable platform for the development of a human experimental model to study hematopoiesis and to explore novel treatments for leukemia.

Biosensors for the analysis of microbiological and chemical contaminants in food

Increases in food production and the ever-present threat of food contamination from microbiological and chemical sources have led the food industry and regulators to pursue rapid, inexpensive methods of analysis to safeguard the health and safety of the consumer. Although sophisticated techniques such as chromatography and spectrometry provide more accurate and conclusive results, screening tests allow a much higher throughput of samples at a lower cost and with less operator training, so larger numbers of samples can be analysed. Biosensors combine a biological recognition element (enzyme, antibody, receptor) with a transducer to produce a measurable signal proportional to the extent of interaction between the recognition element and the analyte. The different uses of the biosensing instrumentation available today are extremely varied, with food analysis as an emerging and growing application. The advantages offered by biosensors over other screening methods such as radioimmunoassay, enzyme-linked immunosorbent assay, fluorescence immunoassay and luminescence immunoassay, with respect to food analysis, include automation, improved reproducibility, speed of analysis and real-time analysis. This article will provide a brief footing in history before reviewing the latest developments in biosensor applications for analysis of food contaminants (January 2007 to December 2010), focusing on the detection of pathogens, toxins, pesticides and veterinary drug residues by biosensors, with emphasis on articles showing data in food matrices. The main areas of development common to these groups of contaminants include multiplexing, the ability to simultaneously analyse a sample for more than one contaminant and portability. Biosensors currently have an important role in food safety; further advances in the technology, reagents and sample handling will surely reinforce this position.

Fetal development, mechanobiology and optimal control processes can improve vascular tissue regeneration in bioreactors: an integrative review

Vascular tissue engineering aims to regenerate blood vessels to replace diseased arteries for cardiovascular patients. With the scaffold-based approach, cells are seeded on a scaffold showing specific properties and are expected to proliferate and self-organize into a functional vascular tissue. Bioreactors can significantly contribute to this objective by providing a suitable environment for the maturation of the tissue engineered blood vessel. It is recognized from the mechanotransduction principles that mechanical stimuli can influence the protein synthesis of the extra-cellular matrix thus leading to maturation and organization of the tissues. Up to date, no bioreactor is especially conceived to take advantage of the mechanobiology and optimize the construct maturation through an advanced control strategy. In this review, experimental strategies in the field of vascular tissue engineering are detailed, and a new approach inspired by fetal development, mechanobiology and optimal control paradigms is proposed. In this new approach, the culture conditions (i.e. flow, circumferential strain, pressure frequency, and others) are supposed to dynamically evolve to match the maturity of vascular constructs and maximize the efficiency of the regeneration process. Moreover, this approach allows the investigation of the mechanisms of growth, remodeling and mechanotransduction during the culture.

Stem cell cultivation in bioreactors

Cell-based therapies have generated great interest in the scientific and medical communities, and stem cells in particular are very appealing for regenerative medicine, drug screening and other biomedical applications. These unspecialized cells have unlimited self-renewal capacity and the remarkable ability to produce mature cells with specialized functions, such as blood cells, nerve cells or cardiac muscle. However, the actual number of cells that can be obtained from available donors is very low. One possible solution for the generation of relevant numbers of cells for several applications is to scale-up the culture of these cells in vitro. This review describes recent developments in the cultivation of stem cells in bioreactors, particularly considerations regarding critical culture parameters, possible bioreactor configurations, and integration of novel technologies in the bioprocess development stage. We expect that this review will provide updated and detailed information focusing on the systematic production of stem cell products in compliance with regulatory guidelines, while using robust and cost-effective approaches.

Current understanding and challenges in bioprocessing of stem cell-based therapies for regenerative medicine

BACKGROUND

A novel manufacturing industry is emerging to translate unique cellular therapy bioprocesses to robust, scaled manufacturing production for successful clinical translation.

SOURCE OF DATA

This review summarizes key translational issues, and current and future perspectives to improve translation of cell-based therapy bioprocessing, based on literature search and author research.

AREAS OF AGREEMENT

It is widely recognized that cell-based therapies could revolutionize health care for a range of diseases, and that there are gaps in the overarching framework and technologies to generate clinical success.

AREAS OF CONTROVERSY

There is limited understanding of how to fulfil requirements as regulatory and manufacturing guidelines are incomplete and few have achieved commercialization.

GROWING POINTS

Recent developments are encouraging adoption of automation and quality engineering approaches for bioprocessing of cell-based therapies.

AREAS TIMELY FOR DEVELOPING RESEARCH

Include technology development to improve the cost and purity of manufacture and final product quality.

How to optimize maturation in a bioreactor for vascular tissue engineering: focus on a decision algorithm for experimental planning

Bioreactors may become essential tools for developing tissue-engineered organs from cells, with or without scaffolds. Cells seeded in these devices are expected to grow and form a tissue. Up to now, one of the main challenges to successfully develop functional organs is the structural organization of the cells into the scaffold during maturation in the bioreactor. The maturation step is affected by a set of highly interlinked dynamical variables (flow, stress, pH, temperature, and growth factors) in such a way that fixing the optimal environmental conditions becomes very complex. This work focuses on how the experimental parameters in the bioreactor can be optimized through numerical modeling to maximize tissue growth. Genetic programming (GP) and Markov decision processes (MDPs) were used in synergy to generate and take full advantage of a model of the vascular construct growth. The approach consists in formulating a model through GP to explain the growth of the construct and using MDPs to come up with a strategy to yield the best results in the experimental runs. Construct growth was improved, and the regeneration process was better understood in numerical simulations that relied on this control system. Therefore, an advanced numerical controller of this type could become an effective and inexpensive tool for planning experimental work in tissue engineering.

Stem cell bioprocessing: fundamentals and principles

In recent years, the potential of stem cell research for tissue engineering-based therapies and regenerative medicine clinical applications has become well established. In 2006, Chung pioneered the first entire organ transplant using adult stem cells and a scaffold for clinical evaluation. With this a new milestone was achieved, with seven patients with myelomeningocele receiving stem cell-derived bladder transplants resulting in substantial improvements in their quality of life. While a bladder is a relatively simple organ, the breakthrough highlights the incredible benefits that can be gained from the cross-disciplinary nature of tissue engineering and regenerative medicine (TERM) that encompasses stem cell research and stem cell bioprocessing. Unquestionably, the development of bioprocess technologies for the transfer of the current laboratory-based practice of stem cell tissue culture to the clinic as therapeutics necessitates the application of engineering principles and practices to achieve control, reproducibility, automation, validation and safety of the process and the product. The successful translation will require contributions from fundamental research (from developmental biology to the 'omics' technologies and advances in immunology) and from existing industrial practice (biologics), especially on automation, quality assurance and regulation. The timely development, integration and execution of various components will be critical-failures of the past (such as in the commercialization of skin equivalents) on marketing, pricing, production and advertising should not be repeated. This review aims to address the principles required for successful stem cell bioprocessing so that they can be applied deftly to clinical applications.

Bringing diagnostic technologies to the clinical laboratory: Rigor, regulation, and reality

With the numerous reports of new technologies and biomarkers reported in the literature, it may be surprising that there are not an equal number of new products available to the clinical diagnostic laboratory. Powerful potential tools such as protein microarrays and MS patterns have been extensively published yet commercialization and acceptance of these technologies has yet to happen. The reasons for this are a combination of industry risk avoidance, academic focus on discovery, and a lack of appreciation for the high standards and regulation that surrounds the clinical diagnostic laboratory. The development and validation of a new technology or biomarker ensures that a test is reproducible, controllable, and has a defined accuracy and clinical predictive result but this information is only obtained through somewhat mundane but necessary experimental work. The use of design of experiment principles helps to define material parameters to ensure performance. The organization and documentation of this work through a quality system is both mandated and practical. All of this must be done before a test can reach the market with the safety and effectiveness review of regulatory agencies.

A real-time multi-channel monitoring system for stem cell culture process

A novel, up to 128 channels, multi-parametric physiological measurement system suitable for monitoring hematopoietic stem cell culture processes and cell cultures in general is presented in this paper. The system aims to measure in real-time the most important physical and chemical culture parameters of hematopoietic stem cells, including physicochemical parameters, nutrients, and metabolites, in a long-term culture process. The overarching scope of this research effort is to control and optimize the whole bioprocess by means of the acquisition of real-time quantitative physiological information from the culture. The system is designed in a modular manner. Each hardware module can operate as an independent gain programmable, level shift adjustable, 16 channel data acquisition system specific to a sensor type. Up to eight such data acquisition modules can be combined and connected to the host PC to realize the whole system hardware. The control of data acquisition and the subsequent management of data is performed by the system's software which is coded in LabVIEW. Preliminary experimental results presented here show that the system not only has the ability to interface to various types of sensors allowing the monitoring of different types of culture parameters. Moreover, it can capture dynamic variations of culture parameters by means of real-time multi-channel measurements thus providing additional information on both temporal and spatial profiles of these parameters within a bioreactor. The system is by no means constrained in the hematopoietic stem cell culture field only. It is suitable for cell growth monitoring applications in general.

Expansion of human hematopoietic stem cells for transplantation: trends and perspectives

Umbilical cord blood transplantation is clinically limited by its low progenitor cell content. Ex vivo expansion has become an alternative to increase the cell dose available for transplants. Expansion has been evaluated in several ways such as static cultures combining growth factors or mimicking the natural microenvironment using co-culture systems. However, static cultures have a small volume capacity and therefore large-scale expansion has been addressed using bioreactors. These and other biotechnological approaches for the expansion of hematopoietic progenitors and their utility to study several aspects of hematopoietic stem cell biology are discussed here.