Hematopoietic Stem Cells Culture, Expansion and Differentiation: An Insight into Variable and Available Media

Mesenchymal progenitor cells from non-inflamed versus inflamed synovium post-ACL injury present with distinct phenotypes and cartilage regeneration capacity

BACKGROUND

Osteoarthritis (OA) is a chronic debilitating disease impacting a significant percentage of the global population. While there are numerous surgical and non-invasive interventions that can postpone joint replacement, there are no current treatments which can reverse the joint damage occurring during the pathogenesis of the disease. While many groups are investigating the use of stem cell therapies in the treatment of OA, we still don't have a clear understanding of the role of these cells in the body, including heterogeneity of tissue resident adult mesenchymal progenitor cells (MPCs).

METHODS

In the current study, we examined MPCs from the synovium and individuals with or without a traumatic knee joint injury and explored the chondrogenic differentiation capacity of these MPCs in vitro and in vivo.

RESULTS

We found that there is heterogeneity of MPCs with the adult synovium and distinct sub-populations of MPCs and the abundancy of these sub-populations change with joint injury. Furthermore, only some of these sub-populations have the ability to effect cartilage repair in vivo. Using an unbiased proteomics approach, we were able to identify cell surface markers that identify this pro-chondrogenic MPC population in normal and injured joints, specifically CD82^LowCD59⁺ synovial MPCs have robust cartilage regenerative properties in vivo.

CONCLUSIONS

The results of this study clearly show that cells within the adult human joint can impact cartilage repair and that these sub-populations exist within joints that have undergone a traumatic joint injury. Therefore, these populations can be exploited for the treatment of cartilage injuries and OA in future clinical trials.

Biophysical cues of bone marrow-inspired scaffolds regulate hematopoiesis of hematopoietic stem and progenitor cells

Hematopoietic stem cells (HSCs) are adult multipotential stem cells with the capacity to differentiate into all blood cells and immune cells, which are essential for maintaining hematopoietic homeostasis throughout the lifespan and reconstituting damaged hematopoietic system after myeloablation. However, the clinical application of HSCs is hindered by the imbalance of its self-renewal and differentiation during in vitro culture. Considering the fact that HSC fate is uniquely determined by natural bone marrow microenvironment, various elaborate cues in this hematopoietic micro-niche provide an excellent reference for the regulation of HSCs. Inspired by the bone marrow extracellular matrix (ECM) network, we designed degradable scaffolds by orchestrating the physical parameters to investigate the decoupling effects of Young's modulus and pore size of three-dimensional (3D) matrix materials on the fate of hematopoietic stem and progenitor cells (HSPCs). We ascertained that the scaffold with larger pore size (80 μm) and higher Young's modulus (70 kPa) was more favorable for HSPCs proliferation and the maintenance of stemness related phenotypes. Through in vivo transplantation, we further validated that scaffolds with higher Young's modulus were more propitious in maintaining the hematopoietic function of HSPCs. We systematically screened an optimized scaffold for HSPC culture which could significantly improve the cell function and self-renewal ability compared with traditional two-dimensional (2D) culture. Together, these results indicate the important role of biophysical cues in regulating HSC fate and pave the way for the parameter design of 3D HSC culture system.

Therapeutic targeting and HSC proliferation by small molecules and biologicals

Hematopoietic stem cells (HSCs) have considerably therapeutic value on autologous and allogeneic transplantation for many malignant/non-malignant hematological diseases, especially with improvement of gene therapy. However, acquirement of limited cell dose from HSC sources is the main handicap for successful transplantation. Therefore, many strategies based on the utilization of various cytokines, interaction of stromal cells, modulation of several extrinsic and intrinsic factors have been developed to promote ex vivo functional HSC expansion with high reconstitution ability until today. Besides all these strategies, small molecules become prominent with their ease of use and various advantages when they are translated to the clinic. In the last two decades, several small molecule compounds have been investigated in pre-clinical studies and, some of them were evaluated in different stages of clinical trials for their safety and efficiencies. In this chapter, we will present an overview of HSC biology, function, regulation and also, pharmacological HSC modulation with small molecules from pre-clinical and clinical perspectives.

Skewed fate and hematopoiesis of CD34+ HSPCs in umbilical cord blood amid the COVID-19 pandemic

Umbilical cord blood (UCB) is an irreplaceable source for hematopoietic stem progenitor cells (HSPCs). However, the effects of SARS-CoV-2 infection and COVID-19 vaccination on UCB phenotype, specifically the HSPCs therein, are currently unknown. We thus evaluated any effects of SARS-CoV-2 infection and/or COVID-19 vaccination from the mother on the fate and functionalities of HSPCs in the UCB. The numbers and frequencies of HSPCs in the UCB decreased significantly in donors with previous SARS-CoV-2 infection and more so with COVID-19 vaccination via the induction of apoptosis, likely mediated by IFN-γ-dependent pathways. Two independent hematopoiesis assays, a colony forming unit assay and a mouse humanization assay, revealed skewed hematopoiesis of HSPCs obtained from donors delivered from mothers with SARS-CoV-2 infection history. These results indicate that SARS-CoV-2 infection and COVID-19 vaccination impair the functionalities and survivability of HSPCs in the UCB, which would make unprecedented concerns on the future of HSPC-based therapies.

Development and clinical translation considerations for the next wave of gene modified hematopoietic stem and progenitor cells therapies

INTRODUCTION

Consistent and reliable manufacture of gene modified hematopoietic stem and progenitor cell (HPSC) therapies will be of the utmost importance as they become more mainstream and address larger populations. Robust development campaigns will be needed to ensure that these products will be delivered to patients with the highest quality standards.

AREAS COVERED

Through publicly available manuscripts, press releases, and news articles - this review touches on aspects related to HSPC therapy, development, and manufacturing.

EXPERT OPINION

Recent advances in genome modification technology coupled with the longstanding clinical success of HSPCs warrants great optimism for the next generation of engineered HSPC-based therapies. Treatments for some diseases that have thus far been intractable now appear within reach. Reproducible manufacturing will be of critical importance in delivering these therapies but will be challenging due to the need for bespoke materials and methods in combination with the lack of off-the-shelf solutions. Continued progress in the field will manifest in the form of industrialization which currently requires attention and resources directed toward the custom reagents, a focus on closed and automated processes, and safer and more precise genome modification technologies that will enable broader, faster, and safer access to these life-changing therapies.

Advances in Model Systems for Human Cytomegalovirus Latency and Reactivation

Human cytomegalovirus (HCMV) is a highly prevalent beta-herpesvirus and a significant cause of morbidity and mortality following hematopoietic and solid organ transplant, as well as the leading viral cause of congenital abnormalities. A key feature of the pathogenesis of HCMV is the ability of the virus to establish a latent infection in hematopoietic progenitor and myeloid lineage cells. The study of HCMV latency has been hampered by difficulties in obtaining and culturing primary cells, as well as an inability to quantitatively measure reactivating virus, but recent advances in both in vitro and in vivo models of HCMV latency and reactivation have led to a greater understanding of the interplay between host and virus. Key differences in established model systems have also led to controversy surrounding the role of viral gene products in latency establishment, maintenance, and reactivation. This review will discuss the details and challenges of various models including hematopoietic progenitor cells, monocytes, cell lines, and humanized mice. We highlight the utility and functional differences between these models and the necessary experimental design required to define latency and reactivation, which will help to generate a more complete picture of HCMV infection of myeloid-lineage cells.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.