Long-term stability, functional competence, and safety of microencapsulated specific pathogen-free neonatal porcine Sertoli cells: a potential product for cell transplant therapy

Effects and Mechanisms Activated by Treatment with Cationic, Anionic and Zwitterionic Liposomes on an In Vitro Model of Porcine Pre-Pubertal Sertoli Cells

Liposomes have been successfully used as drug-delivery vehicles, but there are no clinical studies on improved fertility and the few reported experimental studies have been performed in animal models far from humans. The aim of this paper was to study the effects of treatment with cationic, anionic and zwitterionic liposomes on our superior mammalian model of porcine prepubertal Sertoli cells (SCs) to find a carrier of in vitro test drugs for SCs. Porcine pre-pubertal SCs cultures were incubated with different liposomes. Viability, apoptosis/necrosis status (Annexin-V/Propidium iodide assay), immunolocalisation of β-actin, vimentin, the phosphorylated form of AMP-activated protein Kinase (AMPK)α and cell ultrastructure (Transmission Electron Microscopy, TEM) were analysed. Zwitterionic liposomes did not determine changes in the cell cytoplasm. The incubation with anionic and cationic liposomes modified the distribution of actin and vimentin filaments and increased the levels of the phosphorylated form of AMPKα. The Annexin/Propidium Iodide assay suggested an increase in apoptosis. TEM analysis highlighted a cytoplasmic vacuolisation. In conclusion, these preliminary data indicated that zwitterionic liposomes were the best carrier to use in an in vitro study of SCs to understand the effects of molecules or drugs that could have a clinical application in the treatment of certain forms of male infertility.

Microencapsulated Sertoli cells sustain myoblast proliferation without affecting the myogenic potential. In vitro data

Sertoli cells (SeC) isolated from porcine testes have shown direct effects on muscle precursor cells sustaining C2C12 myoblasts proliferation and inhibiting oxidative stress and apoptosis in the early phase of the differentiation process, and stimulating myoblast fusion into myotubes and the expression of markers of myogenic differentiation in the late phase. This suggested that the cocktail of factors secreted by SeC stimulates proliferation in myoblasts without weakening their myogenic potential resulting in the formation of the critical myoblast amount necessary to rebuild the required muscle mass upon a damage. Here, we show that co-culturing C2C12 myoblasts with high doses of SeC microencapsulated in clinical grade alginate-based microcapsules (MC-SeC) for three days in differentiation medium (DM) translates into increased cell numbers and almost absence of myotube formation. However, after removal of MC-SeC, an intense fusion activity into myotubes was observed culminating in a fusion index similar to that of control after additional three days of culture in DM. These data definitely demonstrate that SeC-derived factors preserve the myogenic potential while sustaining cell proliferation in C2C12 myoblasts.

Effects of Titanium Dioxide Nanoparticles on Porcine Prepubertal Sertoli Cells: An "In Vitro" Study

The increasing use of nanomaterials in a variety of industrial, commercial, medical products, and their environmental spreading has raised concerns regarding their potential toxicity on human health. Titanium dioxide nanoparticles (TiO2 NPs) represent one of the most commonly used nanoparticles. Emerging evidence suggested that exposure to TiO2 NPs induced reproductive toxicity in male animals. In this in vitro study, porcine prepubertal Sertoli cells (SCs) have undergone acute (24 h) and chronic (from 1 up to 3 weeks) exposures at both subtoxic (5 µg/ml) and toxic (100 µg/ml) doses of TiO2 NPs. After performing synthesis and characterization of nanoparticles, we focused on SCs morphological/ultrastructural analysis, apoptosis, and functionality (AMH, inhibin B), ROS production and oxidative DNA damage, gene expression of antioxidant enzymes, proinflammatory/immunomodulatory cytokines, and MAPK kinase signaling pathway. We found that 5 µg/ml TiO2 NPs did not induce substantial morphological changes overtime, but ultrastructural alterations appeared at the third week. Conversely, SCs exposed to 100 µg/ml TiO2 NPs throughout the whole experiment showed morphological and ultrastructural modifications. TiO2 NPs exposure, at each concentration, induced the activation of caspase-3 at the first and second week. AMH and inhibin B gene expression significantly decreased up to the third week at both concentrations of nanoparticles. The toxic dose of TiO2 NPs induced a marked increase of intracellular ROS and DNA damage at all exposure times. At both concentrations, the increased gene expression of antioxidant enzymes such as SOD and HO-1 was observed whereas, at the toxic dose, a clear proinflammatory stress was evaluated along with the steady increase in the gene expression of IL-1α and IL-6. At both concentrations, an increased phosphorylation ratio of p-ERK1/2 was observed up to the second week followed by the increased phosphorylation ratio of p-NF-kB in the chronic exposure. Although in vitro, this pilot study highlights the adverse effects even of subtoxic dose of TiO2 NPs on porcine prepubertal SCs functionality and viability and, more importantly, set the basis for further in vivo studies, especially in chronic exposure at subtoxic dose of TiO2 NPs, a condition closer to the human exposure to this nanoagent.

Fertility Preservation and Restoration Options for Pre-Pubertal Male Cancer Patients: Current Approaches

Fertility preservation for prepubertal male patients undergoing gonadotoxic therapies, potentially depleting spermatogonial cells, is an expanding necessity, yet most of the feasible options are still in the experimental phase. We present our experience and a summary of current and novel possibilities regarding the different strategies to protect or restore fertility in young male patients, before proceeding with chemotherapy or radiotherapy for malignances or other diseases. Adult oncological patients should always be counselled to cryopreserve the semen before starting treatment, however this approach is not suitable for prepubertal boys, who aren't capable to produce sperm yet. Fortunately, since the survival rate of pediatric cancer patients has skyrocketed in the last decade and it's over 84%, safeguarding their future fertility is becoming a major concern for reproductive medicine. Surgical and medical approaches to personalize treatment or protect the gonads could be a valid first step to take. Testicular tissue autologous grafting or xenografting, and spermatogonial stem cells (SSCs) transplantation, are the main experimental options available, but spermatogenesis in vitro is becoming an intriguing alternative. All of these methods feature both strong and weak prospects. There is also relevant controversy regarding the type of testicular material to preserve and the cryopreservation methods. Since transplanted cells are bound to survive based on SSCs number, many ways to enrich their population in cultures have been proposed, as well as different sites of injection inside the testis. Testicular tissue graft has been experimented on mice, rabbits, rhesus macaques and porcine, allowing the birth of live offspring after performing intracytoplasmic sperm injection (ICSI), however it has never been performed on human males yet. In vitro spermatogenesis remains a mirage, although many steps in the right direction have been performed. The manufacturing of 3D scaffolds and artificial spermatogenetic niche, providing support to stem cells in cultures, seems like the best way to further advance in this field.

Effect of EPA on Neonatal Pig Sertoli Cells "In Vitro": A Possible Treatment to Help Maintain Fertility in Pre-Pubertal Boys Undergoing Treatment With Gonado-Toxic Therapies

The incidence of cancer in pre-pubertal boys has significantly increased and, it has been recognized that the gonado-toxic effect of the cancer treatments may lead to infertility. Here, we have evaluated the effects on porcine neonatal Sertoli cells (SCs) of three commonly used chemotherapy drugs; cisplatin, 4-Hydroperoxycyclophosphamide and doxorubicin. All three drugs induced a statistical reduction of 5-hydroxymethylcytosine in comparison with the control group, performed by Immunofluorescence Analysis. The gene and protein expression levels of GDNF, were significantly down-regulated after treatment to all three chemotherapy drugs comparison with the control group. Specifically, differences in the mRNA levels of GDNF were: 0,8200 ± 0,0440, 0,6400 ± 0,0140, 0,4400 ± 0,0130 fold change at 0.33, 1.66, and 3.33μM cisplatin concentrations, respectively (**p < 0.01 at 0.33 and 1.66 μM vs SCs and ***p < 0.001 at 3.33μM vs SCs); 0,6000 ± 0,0340, 0,4200 ± 0,0130 fold change at 50 and 100 μM of 4-Hydroperoxycyclophosphamide concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,7000 ± 0,0340, 0,6200 ± 0,0240, 0,4000 ± 0,0230 fold change at 0.1, 0.2 and 1 µM doxorubicin concentrations, respectively (**p < 0.01 at 0.1 and 0.2 μM vs SCs and ***p < 0.001 at 1 μM vs SCs). Differences in the protein expression levels of GDNF were: 0,7400 ± 0,0340, 0,2000 ± 0,0240, 0,0400 ± 0,0230 A.U. at 0.33, 1.66, and 3.33μM cisplatin concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,7300 ± 0,0340, 0,4000 ± 0,0130 A.U. at 50 and 100 μM of 4- Hydroperoxycyclophosphamide concentrations, respectively (**p < 0.01 at both these concentrations vs SCs); 0,6200 ± 0,0340, 0,4000 ± 0,0240, 0,3800 ± 0,0230 A.U. at 0.l, 0.2 and 1 µM doxorubicin concentrations, respectively (**p < 0.01 at 0.1 and 0.2 μM vs SCs and ***p < 0.001 at 1 μM vs SCs). Furthermore, we have demonstrated the protective effect of eicosapentaenoic acid on SCs only at the highest concentration of cisplatin, resulting in an increase in both gene and protein expression levels of GDNF (1,3400 ± 0,0280 fold change; **p < 0.01 vs SCs); and of AMH and inhibin B that were significantly recovered with values comparable to the control group. Results from this study, offers the opportunity to develop future therapeutic strategies for male fertility management, especially in pre-pubertal boys.

DoE Analysis of Approaches for Hydrogel Microbeads' Preparation by Millifluidic Methods

Hydrogel microbeads hold great promise for immune-protective cell transplants and in vitro studies. Millifluidic generation of hydrogel microbeads is a highly efficient and reproducible approach enabling a mass production. This paper illustrates the preparation and characterization of highly controlled and reproducible microbeads made by different types of hydrogel using millifluidic approaches. The optimization of the process was made by a design of experiments (DoE) approach. The microbeads' large-scale production can be potentially used for single cells or clusters encapsulation.

Anti-Müllerian hormone production in the ovary: a comparative study in bovine and porcine granulosa cells†

In this study, we aimed to determine the origin of the difference, in terms of anti-Müllerian hormone production, existing between the bovine and porcine ovaries. We first confirmed by quantitative real-time-Polymerase-Chain Reaction, ELISA assay and immunohistochemistry that anti-Müllerian hormone mRNA and protein production are very low in porcine ovarian growing follicles compared to bovine ones. We then have transfected porcine and bovine granulosa cells with vectors containing the luciferase gene driven by the porcine or the bovine anti-Müllerian hormone promoter. These transfection experiments showed that the porcine anti-Müllerian hormone promoter is less active and less responsive to bone morphogenetic protein stimulations than the bovine promoter in both porcine and bovine cells. Moreover, bovine but not porcine granulosa cells were responsive to bone morphogenetic protein stimulation after transfection of a plasmidic construction including a strong response element to the bone morphogenetic proteins (12 repetitions of the GCCG sequence) upstream of the luciferase reporter gene. We also showed that SMAD6, an inhibitor of the SMAD1-5-8 pathway, is strongly expressed in porcine compared to the bovine granulosa cells. Overall, these results suggest that the low expression of anti-Müllerian hormone in porcine growing follicles is due to both a lack of activity/sensitivity of the porcine anti-Müllerian hormone promoter, and to the lack of responsiveness of porcine granulosa cells to bone morphogenetic protein signaling, potentially due to an overexpression of SMAD6 compared to bovine granulosa cells. We propose that the low levels of anti-Müllerian hormone in the pig would explain the poly-ovulatory phenotype in this species.

Effects of GH and IGF1 on Basal and FSH-Modulated Porcine Sertoli Cells In-Vitro

Several lines of evidence suggest that insulin-like growth factor 1 (IGF1) is involved in Sertoli cell (SC) proliferation and that its receptor (IGF1R) could mediate follicle-stimulating hormone (FSH) effects. To examine the role of the growth hormone (GH)-IGF1 axis on SC function, we evaluated the effects of GH and IGF1 on basal and FSH-modulated SC proliferation, as well as on anti-Müllerian hormone (AMH) and inhibin B expression and secretion in-vitro. SCs from neonatal pigs were incubated with (1) placebo, (2) 100 nM highly purified urofollitropin (hpFSH), (3) 100 nM recombinant GH (rGH), (4) 100 nM recombinant IGF1 (rIGF1), (5) 100 nM hpFSH plus 100 nM rGH, (6) 100 nM hpFSH plus 100 nM rIGF1, for 48 h. We found that IGF1, but not FSH nor GH, stimulated SC proliferation. Furthermore, an inhibitory effect of FSH, GH and IGF1 on AMH secretion, and a stimulatory role of FSH and IGF1, but not GH, on inhibin B secretion were found. These results suggest that the GH-IGF1 axis influences basal and FSH-modulated SC proliferation and function. We speculate that SC proliferation occurring in childhood might be supported by the increased serum IGF1 levels observed during this period of life.

Effects of Insulin on Porcine Neonatal Sertoli Cell Responsiveness to FSH In Vitro

There is ongoing debate as to whether the decline of sperm production in recent times may be related to a parallel increase in the rate of obesity and diabetes. Lower anti-Müllerian hormone (AMH) and inhibin B secretion have been observed in young hyperinsulinemic patients compared to healthy controls, suggesting a Sertoli cell (SC) dysfunction. The pathophysiological mechanisms underlying SC dysfunction in these patients are poorly understood. To the best of our knowledge, no evidence is available on the effects of insulin on SC function. Therefore, this study was undertaken to assess the effects of insulin on basal and follicle-stimulating hormone (FSH)-stimulated SC function in vitro. To accomplish this, we evaluated the expression of AMH, inhibin B and FSHR genes, the secretion of AMH and inhibin B and the phosphorylation of AKT473 and SC proliferation on neonatal porcine SC after incubation with FSH and/or insulin. We found that similar to FSH, the expression and secretion of AMH is suppressed by insulin. Co-incubation with FSH and insulin decreased AMH secretion significantly more than with FSH alone. Insulin had no effect on the expression and secretion of the inhibin B gene, but co-incubation with FSH and insulin had a lower effect on inhibin B secretion than that found with FSH alone. FSH and/or insulin increased AKT473 phosphorylation and SC proliferation. In conclusion, the results of this study showed that insulin modulates SC function. We hypothesize that hyperinsulinemia may therefore influence testicular function even before puberty begins. Therefore, particular care should be taken to avoid the onset of hyperinsulinemia in children to prevent a future deleterious effect on fertility.

The IGF1 Receptor Is Involved in Follicle-Stimulating Hormone Signaling in Porcine Neonatal Sertoli Cells

Experimental evidence has shown that the IGF1 receptor (IGF1R) is involved in testicular development during embryogenesis. More recently, data gathered from mice granulosa cells and zebrafish spermatogonia suggest that IGF1R has a role in Follicle-stimulating hormone (FSH) signaling. No evidence has been reported on this matter in Sertoli cells (SCs) so far. The aim of the study was to evaluate the role, if any, of the IGF1R in FSH signaling in SCs. The effects of FSH exposure on myosin-phosphatase 1 (MYPT1), ERK 1/2, AKT³⁰⁸, AKT⁴⁷³, c-Jun N-terminal kinase (JNK) phosphorylation and on anti-Müllerian hormone (AMH), inhibin B and FSH receptor (FSHR) mRNA levels were assessed with and without the IGF1R inhibitor NVP-AEW541 in purified and functional porcine neonatal SCs. Pre-treatment with NVP-AEW541 inhibited the FSH-induced MYPT1 and ERK 1/2 phosphorylation, decreased the FSH-dependent Protein kinase B (AKT)³⁰⁸ phosphorylation, but did not affect the FSH-induced AKT⁴⁷³ and JNK phosphorylation rate. It also interfered with the FSH-induced AMH and FSHR down-regulation. No influence was observed on the FSH-stimulated Inhibin B gene expression. Conclusion. These findings support the role of theIGF1R in FSH signaling in porcine SCs. The possible influence of IGF1 stimulation on the FSH-mediated effects on SCs should be further explored.

Do porcine Sertoli cells represent an opportunity for Duchenne muscular dystrophy?

Sertoli cells (SeC) are responsible for the immunoprivileged status of the testis thanks to which allogeneic or xenogeneic engraftments can survive without pharmacological immune suppression if co‐injected with SeC. This peculiar ability of SeC is dependent on secretion of a plethora of factors including maturation factors, hormones, growth factors, cytokines and immunomodulatory factors. The anti‐inflammatory and trophic properties of SeC have been largely exploited in several experimental models of diseases, diabetes being the most studied. Duchenne muscular dystrophy (DMD) is a lethal X‐linked recessive pathology in which lack of functional dystrophin leads to progressive muscle degeneration culminating in loss of locomotion and premature death. Despite a huge effort to find a cure, DMD patients are currently treated with anti‐inflammatory steroids. Recently, encapsulated porcine SeC (MC‐SeC) have been injected ip in the absence of immunosuppression in an animal model of DMD resulting in reduction of muscle inflammation and amelioration of muscle morphology and functionality, thus opening an additional avenue in the treatment of DMD. The novel protocol is endowed with the advantage of being potentially applicable to all the cohort of DMD patients regardless of the mutation. This mini‐review addresses several issues linked to the possible use of MC‐SeC injected ip in dystrophic people.

Testosterone and FSH modulate Sertoli cell extracellular secretion: Proteomic analysis

Spermatogenesis is a highly complicated biological process that occurs in the epithelium of the seminiferous tubules. It is regulated by a complex network of endocrine and paracrine factors and by juxtacrine testicular cross-talk. Sertoli cells (SC) play a key role in spermatogenesis due to their production of trophic, differentiation and immune-modulating factors, but many of the molecular pathways of SC action remain controversial and unclear. Over the last two decades, research has focused on extracellular vesicles as an important mechanism of intercellular communication. The aim of this study was to investigate the presence of extracellular vesicles (EVs) in SC and the modulation of their content in SC after FSH and testosterone stimulation. Highly purified porcine pre-pubertal Sertoli cells were isolated according to previously established methods. After 48 h of culture with FSH or FSH + testosterone stimulation, we identified sertolian EVs containing specific mRNAs. Proteomic analysis of EVs content identified 29 proteins under non-stimulatory conditions, most of which were related to receptor binding activity. FSH stimulation induced increases in inhibin-alpha, inhibin-beta, plakoglobin, haptoglobin, D-3-phosphoglycerate dehydrogenase and sodium/potassium-transporting ATPase in sertolian EVs. Testosterone stimulation enhanced the abundance of inhibin-alpha, inhibin-beta, tissue-type plasminogen activator, epidermal growth factor-like protein 8, elongating factor 1-gamma and D-3-phosphoglycerate dehydrogenase. These results are likely to help determine the unknown molecular secretion of Sertoli cells.

Testosterone and Follicle Stimulating Hormone-Dependent Glyoxalase 1 Up-Regulation Sustains the Viability of Porcine Sertoli Cells through the Control of Hydroimidazolone- and Argpyrimidine-Mediated NF-κB Pathway

Because Sertoli cells (SCs) play a central role in germ cell survival, their death may result in marked germ cell loss and infertility. SCs are the only somatic cells within the seminiferous tubules and are essential for regulating spermatogenesis. Factors that enhance or diminish the viability of SCs may have profound effects on spermatogenesis. Yet the mechanisms underlying the maintenance of SC viability remain largely unknown. Glyoxalase 1 (Glo1) detoxifies methylglyoxal (MG), a highly reactive carbonyl species mainly formed during glycolysis, which is a potent precursor of cytotoxic advanced glycation end products (AGEs). Hydroimidazolone (MG-H1) and argpyrimidine (ArgPyr) are AGEs resulting from MG-mediated post-translational modification of arginine residues in various proteins. The role of Glo1 and MG-derived AGEs in regulating the fate of SCs has never been investigated. By using gene silencing and the specific MG scavenger, aminoguanidine, the authors demonstrate that Glo1, under testosterone and follicle-stimulating hormone control, sustains viability of porcine neonatal SCs through a mechanism involving the NF-κB pathway. Glo1 knockdown induces a mitochondrial apoptotic pathway driven by the intracellular accumulation of MG-H1 and ArgPyr that desensitizes NF-κB signaling by modifying the inhibitor of NF-κB kinase, IKKß. This is the first report describing a role for Glo1 and MG-derived AGEs in SC biology, providing valuable new insights into the potential involvement of this metabolic axis into spermatogenesis.

Acute effects of lead on porcine neonatal Sertoli cells in vitro

Environmental pollution is one of the main factors responsible for reducing fertility in males. Lead is one of the major heavy metal contaminants that impairs several organs; it preferentially accumulates in male reproductive organs and alters sperm quality both in vivo and in vitro. However, the underlying mechanisms remain unclear. Sertoli cells (SCs) provide structural and physiological support to spermatogenic cells within seminiferous tubules. Therefore, changes in SCs affect the developing germ cells and alter spermatogenesis. This study aimed to assess whether exposure to subtoxic doses of adversely affects SC functioning in higher mammals. Purified and functional porcine neonatal SCs were exposed to lead acetate at three different concentrations. Lead exposure decreased the mRNA expression and protein levels of inhibin B and anti-Mullerian hormone (AMH) compared to control, indicating loss of FSH-r integrity in terms of 17-β-oestradiol production under FSH stimulation. In addition, we observed an increase in the mRNA levels of Akt and mTOR, and the phosphorylation of p38 and Akt in SCs exposed to lead at all concentrations compared to unexposed control SCs. In conclusion, lead is toxic to SCs, even at low concentrations, and is expected to alter spermatogenesis.

Xenograft of microencapsulated Sertoli cells restores glucose homeostasis in db/db mice with spontaneous diabetes mellitus

BACKGROUND

Increased abdominal fat and chronic inflammation in the expanded adipose tissue of obesity contribute to the development of insulin resistance and type 2 diabetes mellitus (T2D). The emerging immunoregulatory and anti-inflammatory properties of Sertoli cells have prompted their application to experimental models of autoimmune/inflammatory disorders, including diabetes. The main goal of this work was to verify whether transplantation of microencapsulated prepubertal porcine Sertoli cells (MC-SC) in the subcutaneous abdominal fat depot of spontaneously diabetic and obese db/db mice (homozygous for the diabetes spontaneous mutation [Lepr^db ]) would: (i) improve glucose homeostasis and (ii) modulate local and systemic immune response and adipokines profiles.

METHODS

Porcine prepubertal Sertoli cells were isolated, according to previously established methods and enveloped in Barium alginate microcapsules by a mono air-jet device. MC-SC were then injected in the subcutaneous abdominal fat depot of db/db mice.

RESULTS

We have preliminarily shown that graft of MC-SC restored glucose homeostasis, with normalization of glycated hemoglobin values with improvement of the intraperitoneal glucose tolerance test in 60% of the treated animals. These results were associated with consistent increase, in the adipose tissue, of uncoupling protein 1 expression, regulatory B cells, anti-inflammatory macrophages and a concomitant decrease of proinflammatory macrophages. Furthermore, the treated animals showed a reduction in inducible NOS and proinflammatory molecules and a significant increase in an anti-inflammatory cytokine such as IL-10 along with concomitant rise of circulating adiponectin levels. The anti-hyperglycemic graft effects also emerged from an increased expression of GLUT-4, in conjunction with downregulation of GLUT-2, in skeletal muscle and liver, respectively.

CONCLUSIONS

Preliminarily, xenograft of MC-SC holds promises for an effective cell therapy approach for treatment of experimental T2D.

Terapeutic Potential of Microencapsulated Sertoli Cells in Huntington Disease

INTRODUCTION

Immune dysfunction, promoted by pro-inflammatory cytokines, plays a pivotal role in neurodegeneration associated with Huntington's disease.

AIMS

The aim of this study was to investigate the emerging immunoregulatory and antiinflammatory properties of Sertoli cells in Huntington's disease.

METHODS

The experimental R6/2 mouse model of Huntington's disease was treated by a single intraperitoneal injection of microencapsulated prepubertal porcine Sertoli cells and lifespan, motor performance and striatal inflammatory pattern have been evaluated.

RESULTS

The results of this study demonstrated that a single intraperitoneal injection of microencapsulated prepubertal porcine Sertoli cells uniquely improved performances and extended the life expectancy of R6/2 Huntington's disease mice, by immune dysfunction modulation in brain.

CONCLUSIONS

This study highlights the immunomodulatory and trophic role of Sertoli cells that could be of help in the treatment of neurodegenerative disorders.

Regulation of blood-testis barrier by actin binding proteins and protein kinases

The blood-testis barrier (BTB) is an important ultrastructure in the testis, since the onset of meiosis and spermiogenesis coincides with the establishment of a functional barrier in rodents and humans. It is also noted that a delay in the assembly of a functional BTB following treatment of neonatal rats with drugs such as diethylstilbestrol or adjudin also delays the first wave of spermiation. While the BTB is one of the tightest blood-tissue barriers, it undergoes extensive remodeling, in particular, at stage VIII of the epithelial cycle to facilitate the transport of preleptotene spermatocytes connected in clones across the immunological barrier. Without this timely transport of preleptotene spermatocytes derived from type B spermatogonia, meiosis will be arrested, causing aspermatogenesis. Yet the biology and regulation of the BTB remains largely unexplored since the morphological studies in the 1970s. Recent studies, however, have shed new light on the biology of the BTB. Herein, we critically evaluate some of these findings, illustrating that the Sertoli cell BTB is regulated by actin-binding proteins (ABPs), likely supported by non-receptor protein kinases, to modulate the organization of actin microfilament bundles at the site. Furthermore, microtubule-based cytoskeleton is also working in concert with the actin-based cytoskeleton to confer BTB dynamics. This timely review provides an update on the unique biology and regulation of the BTB based on the latest findings in the field, focusing on the role of ABPs and non-receptor protein kinases.