Conditioning is the intensive preparatory phase that precedes an allogeneic stem cell transplant, in which a patient receives blood-forming cells from a donor. Its purpose is twofold: to wipe out the patient’s diseased bone marrow and malignant cells, and to suppress the immune system enough that the donor cells can engraft rather than being rejected. For decades, many conditioning protocols incorporated total body irradiation, or TBI, because radiation is an effective tool for eradicating malignant cells throughout the body. But irradiating the entire body comes at a cost, particularly for older patients, who face higher risks of organ damage, secondary cancers, and prolonged recovery. Reduced-intensity conditioning regimens were developed precisely to soften this blow, using lower doses of treatment to make transplantation feasible for patients who could never tolerate a myeloablative approach.

One of the most successful reduced-intensity strategies in current use is the Baltimore regimen, which pairs fludarabine with low-dose total body irradiation and high-dose post-transplant cyclophosphamide to prevent graft-versus-host disease. The post-transplant cyclophosphamide component is the crucial innovation: by administering high doses of cyclophosphamide in the days immediately after the donor cells are infused, clinicians can selectively eliminate the rapidly proliferating donor T cells that would otherwise attack the recipient’s tissues, while sparing the slower-dividing stem cells that must rebuild the patient’s blood and immune systems. This approach has transformed haploidentical transplantation, allowing nearly any patient with a healthy relative to serve as a donor.

The problem, as the Grenoble team points out, is that not every transplant center has reliable access to total body irradiation. Radiation oncology capacity varies widely across countries and institutions, and in some settings the logistical burden of coordinating TBI sessions for transplant patients is prohibitive. To address this gap, the researchers evaluated a modified, radiation-free version of the Baltimore regimen, designated FE2B2, which replaces the irradiation component with a combination of fludarabine, cyclophosphamide, and busulfan. Fludarabine is a purine analog that potently suppresses lymphocytes; cyclophosphamide adds further immunosuppression and cytotoxic activity; and busulfan, an alkylating agent, takes over the marrow-ablative role that low-dose radiation would otherwise play. The regimen retains the signature post-transplant high-dose cyclophosphamide for graft-versus-host disease prophylaxis.

To test whether this modified protocol could stand in for the original, the investigators conducted a non-interventional, monocentric, retrospective cohort study at their tertiary care center. They included adult patients over the age of eighteen who had received an HLA haploidentical or mismatched unrelated donor peripheral blood stem cell graft with the non-TBI modified Baltimore conditioning between March 2016 and April 2022. The primary endpoints were overall survival at two and five years after transplantation. Secondary endpoints covered the full spectrum of transplant outcomes: donor engraftment, progression-free survival, non-relapse mortality, graft-versus-host disease-free and relapse-free survival, and the incidence of acute and chronic graft-versus-host disease at the same time points.

The cohort comprised sixty-five patients, and their profile reflects exactly the population for whom such a regimen is designed. The median age of the recipients was sixty-six years, an age at which conventional ablative conditioning would be considered unacceptably toxic by many centers. One-third of the patients carried a hematopoietic cell transplantation-specific comorbidity index score of three or higher, signaling substantial pre-existing health burdens. Forty-three percent of the transplants came from haploidentical family donors, meaning donors who share only half of the patient’s human leukocyte antigens, while fifty-seven percent came from mismatched unrelated donors. Both donor types carry elevated immunologic risk compared with fully matched donors, making the results particularly relevant to patients who lack a well-matched donor option. The median follow-up reached sixty-one months, long enough to capture genuinely durable outcomes.

The engraftment data were unambiguous. Neutrophil engraftment, the first milestone of transplant success indicating that donor cells have taken hold and are producing infection-fighting white blood cells, was achieved in every single patient. Platelet engraftment, which restores clotting capacity and is typically slower and less reliable, occurred in ninety-seven percent of patients. These figures suggest that the busulfan-based, radiation-free conditioning creates a receptive marrow environment as effectively as the irradiation-based original. Graft-versus-host disease rates were also in line with expectations for this transplant setting: the cumulative incidence of grade II-IV acute graft-versus-host disease was forty-five percent, grade III-IV acute disease was fourteen percent, chronic graft-versus-host disease reached twenty percent at both two and five years, and moderate to severe chronic disease affected twelve percent of patients.

Non-relapse mortality, the measure of deaths caused by the transplant procedure itself rather than by returning cancer, was twenty-two percent at two years and twenty-five percent at five years. The authors note that four patients died within the first twenty days after transplant, three from hemorrhagic complications and one from cardiogenic shock secondary to pericarditis, underlining that early toxicity remains a genuine hazard in this fragile population even under a reduced-intensity approach. Survival outcomes were correspondingly moderate: two-year and five-year overall survival stood at forty-eight percent and thirty-seven percent respectively, progression-free survival at forty-three percent and thirty-two percent, and graft-versus-host disease-free, relapse-free survival, a stringent composite endpoint requiring patients to remain free of both relapse and significant graft-versus-host disease, at twenty-nine percent and nineteen percent.

The authors conclude that in their cohort of elderly and frail patients with high-risk disease, the FE2B2 regimen demonstrated acceptable toxicity, with long-term outcomes that align with published data for the classical Baltimore conditioning that includes total body irradiation. In practical terms, this means that centers without access to radiation facilities can offer a defensible alternative without apparently compromising the fundamental transplant outcomes that matter most to patients. Given that roughly half of patients diagnosed with hematologic malignancies are over sixty and that donor availability increasingly favors haploidentical options, a validated radiation-free pathway could meaningfully expand the number of older patients who are offered curative-intent transplantation rather than palliative treatment alone.

The study’s limitations are those inherent to its design. As a retrospective, single-center analysis of sixty-five patients, it cannot deliver the statistical power of a randomized trial, and center-specific supportive care practices may influence outcomes such as early hemorrhagic deaths. A longer median follow-up beyond five years would also sharpen estimates of late relapse and chronic graft-versus-host disease. Nevertheless, the findings add to a growing body of evidence that transplant eligibility need not be dictated by age or by the technological resources of a given hospital. For elderly and unfit patients with high-risk blood cancers and only half-matched or mismatched donors available, the modified Baltimore regimen offers a chemically engineered route to engraftment that requires no radiation at all, bringing a once-exclusive therapy closer to universal availability.

Subject of Research: A non-TBI chemotherapy conditioning regimen for allogeneic stem cell transplantation in elderly or unfit patients with haploidentical or mismatched unrelated donors.

Article Title: A Baltimore-modified non-TBI conditioning for allogeneic stem cell transplantation in elderly or unfit patients with haploidentical or mismatched donors

Article References: Volpari, V., Bulabois, C.-E., Thiebaut-Bertrand, A., Regny, C., Park, S., Carre, M., & Meunier, M. (2026). A Baltimore-modified non-TBI conditioning for allogeneic stem cell transplantation in elderly or unfit patients with haploidentical or mismatched donors. Annals of Hematology. https://doi.org/10.1007/s00277-026-07260-1

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07260-1

Keywords: allogeneic stem cell transplantation, reduced-intensity conditioning, Baltimore regimen, total body irradiation, haploidentical donor, mismatched unrelated donor, post-transplant cyclophosphamide, graft-versus-host disease, non-relapse mortality, elderly patients, busulfan, hematologic malignancies

Sphingolipids occupy a peculiar position in cell biology. They are simultaneously building blocks and messengers. Ceramide, the central molecule of the sphingolipid pathway, is a well-established promoter of apoptosis, the programmed self-destruction of cells. Its breakdown products, sphingosine and sphingosine-1-phosphate, act in the opposite direction, supporting cell survival, proliferation, and differentiation. The balance among these metabolites, maintained by a network of enzymes that synthesize, degrade, and interconvert them, is therefore critical for any tissue undergoing constant cellular renewal. Few tissues fit that description better than the testis, where spermatogenesis demands the precisely choreographed proliferation, differentiation, and selective elimination of germ cells on a continuous cycle. Disrupting this balance, the researchers reasoned, could plausibly underlie the spermatogenic collapse seen in NOA.

To test this hypothesis, the team took a two-pronged approach that combined human data with experimental validation. First, they mined a publicly available microarray dataset, GSE9210, comprising testicular tissue samples from 11 patients with obstructive azoospermia and 47 patients with non-obstructive azoospermia. Because OA patients produce sperm normally, their tissue serves as a useful benchmark for intact spermatogenesis. By screening the transcriptomic data for genes involved in sphingolipid metabolism, the researchers identified 23 such genes that were differentially expressed between the OA and NOA groups. This bioinformatic screen provided the human evidence that sphingolipid biology is systematically altered when sperm production fails, but it could not, on its own, establish whether those changes are a cause or a consequence of the condition.

For that, the researchers turned to a busulfan-induced mouse model. Busulfan is a chemotherapeutic alkylating agent that selectively depletes spermatogonial stem cells and is widely used to generate animals with impaired spermatogenesis. The team treated mice with busulfan and compared their testes with those of untreated controls, eight animals per group. Using quantitative real-time PCR to measure gene expression, immunohistochemistry to localize protein changes within the testicular architecture, and high-performance liquid chromatography (HPLC) to quantify individual lipid metabolites, the researchers assembled a multi-layered picture of what happens to sphingolipid metabolism when the seminiferous tubules are devastated.

The gene expression results were striking. In the busulfan-treated testes, a cohort of genes responsible for breaking down ceramide and building downstream sphingolipids was significantly downregulated. These included Asah1 and Asah2, which encode ceramidases that convert ceramide into sphingosine; Acer1 and Acer2, additional alkaline ceramidases; Cerk, which phosphorylates ceramide toward ceramide-1-phosphate; Elovl1, an elongase that manufactures the very-long-chain fatty acids needed for ceramide synthesis; Sgms1, which produces sphingomyelin from ceramide; and Galc, a galactosidase involved in glycosphingolipid turnover. In parallel, the three sphingomyelinase genes Smpd1, Smpd2, and Smpd3, which cleave sphingomyelin back into ceramide, were significantly upregulated. The overall pattern suggested a metabolic shift favoring ceramide accumulation and sphingolipid depletion, a combination that would be expected to push germ cells toward apoptosis.

The HPLC measurements confirmed that the enzymatic shifts were mirrored by real changes in the lipid pool itself. Levels of four ceramide species, Cer14, Cer16, Cer18, and Cer20, along with sphingosine and sphingosine-1-phosphate, were all significantly reduced in the busulfan-treated testes. The concurrent decline of both pro-apoptotic ceramides and pro-survival sphingosine-1-phosphate may seem paradoxical, but it points to a wholesale collapse of the sphingolipid metabolic network rather than a simple tipping of the balance in one direction. When the machinery for both generating and recycling these lipids is impaired, the fine-grained control over germ cell fate that depends on them is lost, depriving the seminiferous epithelium of signals needed to sustain the delicate sequence of spermatogenic stages.

The immunohistochemical findings connected this metabolic disarray to the inflammatory and cell-death pathways that characterize testicular damage. Busulfan-treated testes showed increased expression of matrix metalloproteinases MMP-2 and MMP-9, enzymes associated with tissue remodeling and inflammation, together with elevated levels of cleaved caspase-3, the executioner enzyme of apoptosis. At the same time, Bcl-2, a key anti-apoptotic protein that normally protects germ cells from premature death, was reduced. All of these changes reached statistical significance. Together they depict a tissue in which the anti-apoptotic safety net has been withdrawn, the apoptotic machinery has been activated, and inflammatory remodeling is underway, a scenario consistent with the loss of germ cells that defines NOA.

The study builds on earlier evidence that individual sphingolipid enzymes are indispensable for male fertility. Sphingomyelin synthase 1, for example, has been shown to be essential for male fertility in mice, and sphingosine-1-phosphate has been demonstrated to inhibit germ cell apoptosis in the human testis. What distinguishes the new work is its systems-level scope: rather than examining one enzyme in isolation, it maps coordinated changes across dozens of genes and multiple metabolite classes, and it anchors those changes in human disease data rather than relying solely on animal models. The convergence of the human bioinformatic screen and the mouse validation significantly strengthens the argument that sphingolipid dysregulation is not an incidental byproduct of testicular damage but a mechanistically relevant feature of spermatogenic failure.

Caveats remain, as they do in any translational study. The busulfan model reproduces the germ cell depletion of NOA but not necessarily its full range of causes, which in patients include genetic defects, hormonal disturbances, and environmental exposures. Correlation between sphingolipid changes and spermatogenic collapse does not yet prove causation, and the specific sequence of events, whether lipid dysregulation triggers apoptosis or follows it, requires targeted interventional studies. Nevertheless, the identification of concrete molecular targets opens tangible therapeutic avenues. If restoring ceramidase activity, sphingomyelin balance, or sphingosine-1-phosphate signaling could rescue germ cells in damaged testes, sphingolipid-modulating drugs, some of which already exist in other therapeutic areas, might one day help men with NOA regain at least partial sperm production.

The broader significance of the findings extends beyond a single diagnosis. Male factor infertility contributes to roughly half of infertile couples, yet in many cases the underlying biology remains unexplained, and treatment options are limited to assisted reproduction rather than genuine restoration of spermatogenesis. By implicating an entire metabolic pathway that is druggable in principle, the study reframes NOA not merely as a developmental dead end but as a potentially correctable biochemical state. The research, supported in part by the Iran National Science Foundation, adds sphingolipid metabolism to the growing list of lipid-mediated processes, alongside steroidogenesis and membrane remodeling, that must be intact for sperm production to proceed. Future work will need to determine whether the same metabolic signature appears in larger patient cohorts and whether pharmacological correction of the pathway can translate into restored fertility, but the study offers something the field has lacked: a specific, measurable, and modifiable molecular axis on which to focus the search for therapies against one of the most challenging forms of male infertility.

Subject of Research: Sphingolipid metabolism dysregulation in non-obstructive azoospermia

Article Title: Dysregulation of Sphingolipid Metabolism in Non-Obstructive Azoospermia: Insights from Bioinformatics and a Busulfan-Induced Mouse Model

Article References: Parvini, M., Ghasemian, F., & Salimy, S. (2026). Dysregulation of Sphingolipid Metabolism in Non-Obstructive Azoospermia: Insights from Bioinformatics and a Busulfan-Induced Mouse Model. Reproductive Sciences. https://doi.org/10.1007/s43032-026-02194-5

Image Credits: AI Generated

DOI: 10.1007/s43032-026-02194-5

Keywords: sphingolipids, ceramide, sphingosine-1-phosphate, azoospermia, spermatogenesis, male infertility, busulfan, apoptosis, testis, reproductive biology, HPLC, bioinformatics

Busulfan is a bifunctional alkylating agent widely used in clinical medicine, at low doses in prolonged regimens for chronic myeloid leukemia and ovarian cancer, and at high doses as a conditioning drug before bone marrow transplantation. Its therapeutic power comes with a notorious cost: the drug preferentially destroys rapidly dividing cells, and spermatogonia, the stem cells of sperm production, sit squarely in the blast zone. Previous work has shown that busulfan triggers oxidative apoptosis in spermatogonial stem cells, depletes the germinal epithelium of seminiferous tubules, and can leave cancer survivors with drastically reduced sperm counts. As cancer diagnoses rise globally and survival rates improve, preserving fertility in young male patients has become an increasingly urgent research priority.

Telfairia occidentalis, known locally as ugu, ewuroko, or ikong-ubong depending on the Nigerian region, is an edible leafy cucurbit whose seeds are consumed as snacks, soup condiments, and fermented seasonings. The plant is rich in essential oils, vitamins, minerals, amino acids, flavonoids such as quercetin and kaempferol, alkaloids, carotenes, and cucurbitacines, which together underpin its documented antioxidant, anti-inflammatory, antidiabetic, and antimicrobial properties. Earlier experiments had already hinted at reproductive benefits: fluted pumpkin seed oil reversed alcohol-induced germ cell loss in Sprague-Dawley rats, co-administration of the seeds with caffeine protected the spermatogenesis score index in Wistar rats, and seed fractions attenuated doxorubicin-induced testicular toxicity. The Port Harcourt team set out to dissect which chemical fractions of the seed drive which effects, using two parallel experimental designs over a 54-day treatment period.

The researchers harvested mature fluted pumpkin pods from a local market in Ogoni, Rivers State, verified the plant identity botanically, and macerated the dried, ground seeds in 60 percent aqueous ethanol. After concentrating the crude extract, they split it with a separation funnel into a hexane fraction enriched in non-polar lipids and a freeze-dried aqueous fraction rich in water-soluble compounds. In the injury study, adult male Wistar rats received busulfan at 15 milligrams per kilogram body weight, injected intraperitoneally once weekly for two weeks, alongside oral doses of the hexane fraction at 50, 100, or 200 milligrams per kilogram given twice weekly for the full 54 days. In the companion study, healthy rats received the aqueous fraction three days weekly at the same dose range, with corn oil serving as the vehicle control in both experiments. The 54-day window was chosen to span a full cycle of spermatogenesis, ensuring that any effect on sperm production could manifest.

The biochemical readouts painted a vivid picture of busulfan’s assault and the hexane fraction’s counteroffensive. Busulfan alone significantly shrank testis weight and the gonado-somatic index, spiked lipid peroxidation as measured by malondialdehyde levels, and raised the activities of catalase, superoxide dismutase, glutathione reductase, and glutathione S-transferase, a constellation of changes signaling severe oxidative stress and a disrupted glutathione redox balance. Testicular marker enzymes including acid and alkaline phosphatase and gamma-glutamyl transpeptidase, all of which climb when the seminiferous epithelium degenerates, were also elevated, while lactate dehydrogenase, essential for germ cell energy metabolism, fell. Co-treatment with the hexane fraction reversed virtually every one of these abnormalities in a dose-dependent manner, restoring glutathione status, quenching lipid peroxidation, normalizing enzyme activities, and recovering testis weight toward control levels, with the 200 milligram per kilogram dose showing the greatest efficacy.

Under the microscope, the contrast was equally striking. Control rats displayed intact seminiferous tubules brimming with the full cast of spermatogenic cells and tuffs of mature spermatozoa in the lumen. Busulfan left the tubules vacuolated, distorted, and stripped of spermatozoa and spermatids, a classic signature of maturation arrest. Animals given the hexane fraction showed markedly better tubular architecture, with intact basement membranes lined by spermatogonia and substantially less degeneration, although the authors note that some tubules still contained reduced germ cell layers, indicating partial rather than complete rescue. Stereological analysis with ImageJ software confirmed that the extract prevented the busulfan-induced collapse of tubular diameter and seminiferous epithelial height at all doses tested.

The aqueous fraction told a different, quieter story in healthy rats. After 54 days of treatment, seminiferous tubular diameter, luminal diameter, tubular cross-sectional area, tubular length per gram of tissue, epithelial thickness, and, most intriguingly, the number of testosterone-producing Leydig cells all increased in proportion to dose. Yet the Johnsen spermatogenesis score index and the counts of spermatogonia, spermatocytes, round spermatids, and Sertoli cells remained unchanged, as did body weight, absolute testis weight, and the gonado-somatic index. The researchers interpret this as an enhancement of the testis’s structural and steroidogenic infrastructure, potentially improving sperm passage and androgen synthesis, without an outright acceleration of sperm cell production.

Gas chromatography-mass spectrometry helped explain the divergent behaviors of the two fractions. The hexane fraction yielded 270 identified metabolites, 17 of them abundant, dominated by long-chain fatty acids and related lipids including squalene, n-hexadecanoic acid, octadecanoic acid, conjugated linoleic acid, alpha-linolenic acid, and an ascorbic acid derivative. Many of these lipids are known antioxidants, consistent with the fraction’s ability to blunt busulfan-driven oxidative injury. The aqueous fraction contained 277 metabolites, 14 of them abundant, including glycerin, a compound previously shown to modulate testicular androgen production and testicular morphology. The authors propose that the lipid repertoire underwrites protection against injury, while water-soluble constituents such as glycerin sculpt testicular stereology.

The team is candid about the limits of the work: the two fractions were tested in different animal models rather than head-to-head, and future studies should isolate individual bioactive compounds, test them in additional models of gonadal injury, and evaluate liver and kidney safety markers before any clinical translation. Still, the convergence of biochemical, histological, stereological, and metabolomic evidence makes a compelling case that a common Nigerian food seed contains separable chemical programs, one that shields the testis from chemotherapy’s collateral damage and another that may bolster its hormonal machinery. For a world in which more than a million new cancer cases are diagnosed annually and male infertility is a feared consequence of cure, that duality is precisely the kind of leads translational reproductive medicine has been searching for.

The decision to study seed fractions separately reflects a broader principle in pharmacognosy research. Crude plant extracts contain hundreds of compounds with varying solubilities, and pooling them can obscure which molecules are actually responsible for a given biological effect. By partitioning the aqueous ethanol extract between hexane and water, the Port Harcourt team effectively separated the seed’s lipid-soluble cargo from its water-soluble constituents, allowing each chemical repertoire to be evaluated on its own terms. This approach mirrors earlier work on other edible plants, where non-polar fractions rich in tocopherols, phytosterols, and unsaturated fatty acids often carry antioxidant activity, while polar fractions contribute different bioactivities.

The choice of busulfan as the injury model deserves note. Because the drug reliably depletes spermatogonial stem cells while sparing the somatic framework of the testis, it has become a standard tool for generating reproducible testicular damage in rodents. It is also used experimentally to condition recipients for spermatogonial stem cell transplantation, a technique being explored as a fertility-preservation strategy for prepubertal boys facing gonadotoxic therapy. Any compound that protects the germinal epithelium in a busulfan model is therefore of interest not only as a potential co-adjuvant during chemotherapy but also as a candidate for improving the efficiency of stem cell-based fertility restoration.

The stereological findings in healthy rats also carry implications for how such plant products should be interpreted. An increase in Leydig cell number without a corresponding rise in spermatogenic cell counts suggests that the aqueous fraction may be acting on the interstitial compartment, the site of testosterone synthesis, rather than on the seminiferous tubules directly. Since adequate intratesticular testosterone is required to maintain the blood-testis barrier and support later stages of sperm development, expanding the Leydig cell population could, in principle, strengthen the hormonal support system on which spermatogenesis depends, even if the immediate effect on germ cell numbers is neutral.

It remains important to temper enthusiasm appropriately. Rodent doses of 50 to 200 milligrams per kilogram are far higher, on a body-weight basis, than what a person would obtain from eating fluted pumpkin seeds as food, and the extract was administered as a concentrated fraction rather than a whole seed matrix. Absorption, metabolism, and distribution of the identified lipids and water-soluble compounds in humans may differ substantially from rats. Moreover, the absence of reported toxicity data in this study means that long-term safety, particularly at high doses, has not been established. These caveats notwithstanding, the study illustrates how a detailed fraction-by-fraction dissection of a traditional food plant can yield mechanistically grounded leads for protecting male reproductive health.

Subject of Research: Protective and enhancing effects of Telfairia occidentalis seed extract fractions on rat testicular function and busulfan-induced testicular injury

Article Title: Hexane fraction of Telfairia occidentalis (Cucurbitaceae) ethanol seed extract ameliorates busulfan-induced testicular damage while aqueous fraction enhances testis function in normal rats

Article References: Abarikwu, S. O., Erekeere, C. K., Timi-Johnson, E., Ogbonnaya, A. O., & Ezim, O. E. (2026). Hexane fraction of Telfairia occidentalis (Cucurbitaceae) ethanol seed extract ameliorates busulfan-induced testicular damage while aqueous fraction enhances testis function in normal rats. Discover Toxicology, 3(1), Article 16. https://doi.org/10.1007/s44339-026-00061-1

Image Credits: AI Generated

DOI: 10.1007/s44339-026-00061-1

Keywords: Telfairia occidentalis, fluted pumpkin seeds, busulfan, testicular damage, spermatogenesis, oxidative stress, Leydig cells, seminiferous tubules, male fertility, phytochemicals, testicular stereology, Discover Toxicology