G.J. (Gerben) Schaaf, PhD

Research Interests 

More than a thousand muscle diseases have been identified, yet only a few have effective treatments. Many start in childhood, severely affecting mobility, breathing, and the muscle’s ability to regenerate. Our research focuses on Pompe disease, a metabolic muscle disorder, where we uncovered defects in stem cell activation and cell fate that drive disease progression. Current therapy is costly and fails to halt decline. By combining pharmacological, genetic, and biological strategies in cellular models, animal studies, and patient material, we aim to restore muscle repair and ultimately translate our findings into curative therapies.

Promoting Rare Disease Research 

Erasmus MC is a leading center for rare disease care and research, hosting over 60 centers of expertise (CoEs). Most CoEs work independently and are not fully aware of the expertise of others, which limits the exchange of ideas and technical support. Increasing collaboration is particularly important in rare disease research, where knowledge and samples are scarce. The EMC Rare Disease Center has formed a think tank platform of five researchers and clinicians with expertise across the scientific and rare disease domain. Together we aim to connect professionals with synergistic experience to accelerate and extend the impact of our research.

Erasmus MC | Rotterdam, The Netherlands | 2023-present | Assistant Professor, Erasmus MC 
Erasmus MC | Rotterdam, The Netherlands | 2012-2023| Post-Doc/Scientist, Erasmus MC 
Erasmus MC | Rotterdam, The Netherlands | 2008-2012 | Junior Group Leader, Erasmus MC Stem Cell Institute
Stanford University | Palo Alto, CA|June 2006 -August 2007 | Post Doc Dept of Neurology (PI Thomas Rando)
Academic Medical Center Amsterdam | Dept of human genetics |Amsterdam, NL|August 2002-June 2006 | Post Doc laboratory Marcel Kool | Gene expression profiling rhabdomyosarcomas
Utrecht University | Utrecht, NL|August 1997-December 2001 | Doctoral program on renal toxicity disease modeling|Doctoral thesis 6 December 2001
Utrecht University | Utrecht, NL|  MSc. Program |June 1997 | MSc (Cum Laude)

1. Domain-substituted IGF2 tag modulates targeting of lentiviral gene therapy for Hunter syndrome. Catalano, F., Stevic, D., Zundo, G., Huizer, T. F., Dammou, Z., Vlaar, E. C., Katsavelis, D., van den Bosch, J. C., van den Hout, H. J. M. P., Oussoren, E., van der Ploeg, A. T., Ruijter, G. J. G., Schaaf, G. & Pijnappel, W. W. M. P. EMBO Mol. Med.(2025) DOI: 10.1038/S44321-025-00314-3.

2. Lentiviral Gene Therapy for Mucopolysaccharidosis II with Tagged Iduronate 2-Sulfatase Prevents Life-Threatening Pathology in Peripheral Tissues But Fails to Correct Cartilage. Catalano, F., Vlaar, E. C., Dammou, Z., Katsavelis, D., Huizer, T. F., Zundo, G., Hoogeveen-Westerveld, M., Oussoren, E., van den Hout, H. J. M. P., Schaaf, G., Pike-Overzet, K., Staal, F. J. T., van der Ploeg, A. T. & Pijnappel, W. W. M. P. Hum. Gene Ther. (2024) DOI: 10.1089/hum.2023.177.

3. Tagged IDS causes efficient and engraftment-independent prevention of brain pathology during lentiviral gene therapy for Mucopolysaccharidosis type II. Catalano, F., Vlaar, E. C., Katsavelis, D., Dammou, Z., Huizer, T. F., van den Bosch, J. C., Hoogeveen-Westerveld, M., van den Hout, H. J. M. P., Oussoren, E., Ruijter, G. J. G., Schaaf, G., Pike-Overzet, K., Staal, F. J. T., van der Ploeg, A. T. & Pijnappel, W. W. M. P. Mol. Ther. Methods Clin. Dev.31, 101149 (2023) DOI: 10.1016/j.omtm.2023.101149.

4. Lysosomal glycogen accumulation in Pompe disease results in disturbed cytoplasmic glycogen metabolism. Canibano-Fraile, R., Harlaar, L., dos Santos, C. A., Hoogeveen-Westerveld, M., Demmers, J. A. A., Snijders, T., Lijnzaad, P., Verdijk, R. M., van der Beek, N. A. M. E., van Doorn, P. A., van der Ploeg, A. T., Brusse, E., Pijnappel, W. W. M. P. & Schaaf, G. J. J. Inherit. Metab. Dis.46, 101–115 (2023) DOI: 10.1002/JIMD.12560.

5. Comparison of the functional and structural characteristics of rare TSC2 variants with clinical and genetic findings. DufnerAlmeida, L. G., Nanhoe, S., Zonta, A., Hosseinzadeh, M., Kom-Gortat, R., Elfferich, P., Schaaf, G., Kenter, A., Kümmel, D., Migone, N., Povey, S., Ekong, R. & Nellist, M. Hum. Mutat. (2020) DOI: 10.1002/humu.23963.

6. Heterogeneous clinical phenotypes and cerebral malformations reflected by rotatin cellular dynamics. Vandervore, L. V et al.Brain142, 867–884 (2019) DOI: 10.1093/brain/awz045.

7. Comparison of the functional and structural characteristics of rare TSC2 variants with clinical and genetic findings. DufnerAlmeida, L. G., Nanhoe, S., Zonta, A., Hosseinzadeh, M., Kom-Gortat, R., Elfferich, P., Schaaf, G., Kenter, A., Kümmel, D., Migone, N., Povey, S., Ekong, R. & Nellist, M. Hum. Mutat. (2019) DOI: 10.1002/humu.23963.

8. Restoring the regenerative balance in neuromuscular disorders: satellite cell activation as therapeutic target in Pompe disease. Schaaf, G., Canibano-Fraile, R., van Gestel, T., van der Ploeg, A. & Pijnappel, W. Ann. Transl. Med.In press, (2019) DOI: 10.21037/atm.2019.04.48.

9. Large-Scale Expansion of Human iPSC-DerivedSkeletalMuscleCellsforDiseaseModelingandCell-BasedTherapeuticStrategies. van der Wal, E., Herrero-Hernandez, P., Wan, R., Broeders, M., in ’t Groen, S. L. M., van Gestel, T. J. M., van IJcken, W. F. J., Cheung, T. H., van der Ploeg, A. T., Schaaf, G. J. & Pijnappel, W. W. M. P. Stem CellReports10, 1975–1990 (2018) DOI: 10.1016/j.stemcr.2018.04.002.

10. Satellite cells maintain regenerative capacity but fail to repair disease-associated muscle damage in mice with Pompe disease. Schaaf, G. J., van Gestel, T. J. M., In ’t Groen, S. L. M., de Jong, B., Boomaars, B., Tarallo, A., Cardone, M., Parenti, G., van der Ploeg, A. T. & Pijnappel, W. W. M. P. Acta Neuropathol. Commun.6, 119 (2018) DOI: 10.1186/s40478-018-0620-3.

11. Large-Scale Expansion of Human iPSC-DerivedSkeletalMuscleCellsforDiseaseModelingandCell-BasedTherapeuticStrategies. van der Wal, E., Herrero-Hernandez, P., Wan, R., Broeders, M., In ’t Groen, S. L. M., van Gestel, T. J. M., van IJcken, W. F. J., Cheung, T. H., van der Ploeg, A. T., Schaaf, G. J. & Pijnappel, W. W. M. P. Stem cellreports10, 1975–1990 (2018) DOI: 10.1016/j.stemcr.2018.04.002.

12. Functional and morphological improvement of skeletal muscle in Pompe disease after forced satellite cell activation. Schaaf, G., van Gestel, T., in ‘t Groen, S., van der Ploeg, A. & Pijnappel, W. Neuromuscul. Disord. (2017) DOI: 10.1016/j.nmd.2017.06.246.

13. Compromised satellite cell activation contributes to continued muscle wasting in Pompe disease. Schaaf, G., van Gestel, T., Brusse, E., Verdijk, R. M., de Coo, I. F. M., van Doorn, P. A., van der Ploeg, A. T. & Pijnappel, P. W. W. M. Mol. Genet. Metab. (2016) DOI: 10.1016/j.ymgme.2015.12.429.

14. Elevated Plasma Cardiac Troponin T Levels Caused by Skeletal Muscle Damage in Pompe Disease. Wens, S. C. A., Schaaf, G. J., Michels, M., Kruijshaar, M. E., Van Gestel, T. J. M., In ’T Groen, S., Pijnenburg, J., Dekkers, D. H. W., Demmers, J. A. A., Verdijk, L. B., Brusse, E., Van Schaik, R. H. N., Van Der Ploeg, A. T., Van Doorn, P. A. & Pijnappel, W. W. M. P. Circ. Cardiovasc. Genet. (2016) DOI: 10.1161/CIRCGENETICS.115.001322.

15. Elevated Plasma Cardiac Troponin T Levels Caused by Skeletal Muscle Damage in Pompe Disease. Wens, S. C. A., Schaaf, G. J., Michels, M., Kruijshaar, M. E., Van Gestel, T. J. M., In ’T Groen, S., Pijnenburg, J., Dekkers, D. H. W., Demmers, J. A. A., Verdijk, L. B., Brusse, E., Van Schaik, R. H. N., Van Der Ploeg, A. T., Van Doorn, P. A. & Pijnappel, W. W. M. P. Circ. Cardiovasc. Genet.9, (2016) DOI: 10.1161/CIRCGENETICS.115.001322.

16. Lack of robust satellite cell activation and muscle regeneration during the progression of Pompe disease. Schaaf, G. J., van Gestel, T. J., Brusse, E., Verdijk, R. M., de Coo, I. F., van Doorn, P. A., van der Ploeg, A. T. & Pijnappel, W. W. Acta Neuropathol. Commun.3, 1–11 (2015) DOI: 10.1186/s40478-015-0243-x.

17. Ex-vivo Expansion of Muscle-Regenerative Cells for the Treatment of Muscle Disorders. Schaaf, G. J. J. Stem Cell Res. Ther.01, 003 (2012) DOI: 10.4172/2157-7633.S11-003.

18. Ex-vivo Expansion of Muscle-Regenerative Cells for the Treatment of Muscle Disorders. Schaaf, G., Sage, F., Stok, M., Brusse, E., Pijnappel, W., Reuser, A. & Ploeg, A. J. Stem CellRes. Ther.S11, 03 (2012) DOI: 10.4172/2157-7633.S11-003.

19. Silencing of SPRY1 Triggers Complete Regression of Rhabdomyosarcoma Tumors Carrying a Mutated RAS Gene. Gerben Schaaf, Mohamed Hamdi, Danny Zwijnenburg, Arjan Lakeman, Dirk Geerts, Rogier Versteeg & Kool, M. Cancer Res.70, (2010).

20. Silencing of SPRY1 triggers complete regression of rhabdomyosarcoma tumors carrying a mutated RAS gene. Schaaf, G., Hamdi, M., Zwijnenburg, D., Lakeman, A., Geerts, D., Versteeg, R. & Kool, M. Cancer Res.70, (2010) DOI: 10.1158/0008-5472.CAN-09-2532.

21. Genomic imbalances in rhabdomyosarcoma cell lines affect expression of genes frequently altered in primary tumors: an approach to identify candidate genes involved in tumor development. Missiaglia, E., Selfe, J., Hamdi, M., Williamson, D., Schaaf, G., Fang, C., Koster, J., Summersgill, B., Messahel, B., Versteeg, R., Pritchard-Jones, K., Kool, M. & Shipley, J. Genes Chromosom. Cancer48, 455–467 (2009).

22. Statistical comparison of two or more SAGE libraries. Schaaf, G. J., van Ruissen, F., van Kampen, A., Kool, M. & Ruijter, J. M. in Serial Analysis of Gene Expression (SAGE) 151–168 (Humana Press, 2008).

23. Scaling of gene expression data allowing the comparison of different gene expression platforms. van Ruissen, F., Schaaf, G. J., Kool, M., Baas, F. & Ruijter, J. M. Methods Mol. Biol.387, 169–183 (2008) DOI: 1-59745-454-0:169 [pii].

24. Scaling of gene expression data allowing the comparison of different gene expression platforms. van Ruissen, F., Schaaf, G. J., Kool, M., Baas, F. & Ruijter, J. M. Methods Mol. Biol.387, (2008).

25. Statistical comparison of two or more SAGE libraries: one tag at a time. Schaaf, G. J., van Ruissen, F., van Kampen, A., Kool, M. & Ruijter, J. M. Methods Mol. Biol. (2008) DOI: 10.1007/978-1-59745-454-4_12.

26. Full transcriptome analysis of rhabdomyosarcoma, normal, and fetal skeletal muscle: statistical comparison of multiple SAGE libraries. Schaaf, G. J., Ruijter, J. M., van Ruissen, F., Zwijnenburg, D. A., Waaijer, R., Valentijn, L. J., Benit-Deekman, J., van Kampen, A. H., Baas, F. & Kool, M. Faseb J19, 404–406 (2005).

27. Full transcriptome analysis of rhabdomyosarcoma, normal, and fetal skeletal muscle: Statistical comparison of multiple SAGE libraries. Schaaf, G. J., Ruijter, J. M., Van Ruissen, F., Zwijnenburg, D. A., Waaijer, R., Valentijn, L. J., Benit-Deekman, J., Van Kampen, A. H. C., Baas, F. & Kool, M. FASEB J.19, (2005) DOI: 10.1096/fj.04-2104fje.

28. Evaluation of the similarity of gene expression data estimated with SAGE and Affymetrix GeneChips. van Ruissen, F., Ruijter, J. M., Schaaf, G. J., Asgharnegad, L., Zwijnenburg, D. A., Kool, M. & Baas, F. BMC Genomics6, 91 (2005) DOI: 10.1186/1471-2164-6-91.

29. Biotransformation studies using rat proximal tubule cells. Schaaf, G. J., Maas, R. F. M. & Fink-Gremmels, J. Curr. Protoc. Toxicol.Chapter 4, Unit4.14 (2004) DOI: 10.1002/0471140856.tx0414s21.

30. Management of oxidative stress by heme oxygenase-1 in cisplatin-induced toxicity in renal tubular cells. Schaaf, G. J., Maas, R. F., de Groene, E. M. & Fink-Gremmels, J. Free RadicRes36, 835–843 (2002).

31. The role of oxidative stress in the ochratoxin A-mediated toxicity in proximal tubular cells. Schaaf, G. J., Nijmeijer, S. M., Maas, R. F. M., Roestenberg, P., De Groene, E. M. & Fink-Gremmels, J. Biochim. Biophys. Acta - Mol. Basis Dis.1588, 149–158 (2002) DOI: 10.1016/S0925-4439(02)00159-X.

32. The role of oxidative stress in the ochratoxin A-mediated toxicity in proximal tubular cells. Schaaf, G. ., Nijmeijer, S. ., Maas, R. F. ., Roestenberg, P., De Groene, E. .& Fink-Gremmels, J. Biochim. Biophys. Acta - Mol. Basis Dis.1588, (2002) DOI: 10.1016/S0925-4439(02)00159-X.

33. The Influence of Glucuronidation on in Vitro Assessment of Bilirubin Production as Measure of HO Activity. Schaaf, G. J., Maas, R. F. M., de Groene, E. M. & Fink-Gremmels, J. in HemeOxygenase in BiologyandMedicine (2002). DOI: 10.1007/978-1-4615-0741-3_31.

34. β-lyase-dependent attenuation of cisplatin-mediated toxicity by selenocysteine Se-conjugates in renal tubular cell lines. Rooseboom, M., Schaaf, G., Commandeur, J. N. M., Vermeulen, N. P. E. & Fink-Gremmels, J. J. Pharmacol. Exp. Ther. (2002) DOI: 10.1124/jpet.301.3.884.

35. Characterization of biotransformation enzyme activities in primary rat proximal tubular cells. Schaaf, G. J., De Groene, E. M., Maas, R. F., Commandeur, J. N. M. & Fink-Gremmels, J. Chem. Biol. Interact. (2001) DOI: 10.1016/S0009-2797(01)00151-X.

36. IGF I induction of p53 requires activation of MAP kinase in cardiac muscle cells. Wang, P. H., Schaaf, G. J., Chen, W.-H., Feng, J., Prins, B. A., Levin, E. R. & Bahl, J. J. Biochem. Biophys. Res. Commun.245, (1998) DOI: 10.1006/bbrc.1998.8540.

37. IGF I induction of p53 requires activation of MAP kinase in cardiac muscle cells. Wang, P. H., Schaaf, G. J., Chen, W. H., Feng, J., Prins, B. A., Levin, E. R. & Bahl, J. J. Biochem. Biophys. Res. Commun. (1998) DOI: 10.1006/bbrc.1998.8540.

38. P I.5 Mutagenicity testing of the mycotoxin ochratoxin A in human cytochrome P450 expressing cell lines. de Groene, E. M., Schaaf, G. J., Horbach, G. J. & Fink-Gremmels, J. Mutat. Res. Mol. Mech. Mutagen. (1997) DOI: 10.1016/s0027-5107(97)82621-8.

Assistant Professor | Erasmus MC | Rotterdam, The Netherlands

2024 and 2025 NWO NWO-ENW Wetenschappelijke Bijeenkomsten en Ontmoetingen WBO |€10 K (2x) | Mainapplicantwith Iris van Moort
2023 Metakids| New biomarkers for Pompe disease to support newborn screening and to monitor disease progression and effect of (innovative) therapy| Co-applicant| €300K
2023-2028 Center for Rare Disease program grant | StichtingVrienden van Sophia|workpackage leadof the Health Date platform (€300K) and co-supervisor of the Innovative Diagnostics workpackage (€300K). 
2020 MRACE pilot project “A dynamic roadmap of satellite cell‐dependent skeletal muscle regeneration” 50K | Co-PI with J. Gribnau (Department of Reproduction; main applicant) and Pim Pijnappel (Department of Pediatrics).
2019: Clinical Genetics Pilot study pilot “In search of a biomarker of disease progression and response to enzyme replacement therapy in Pompe disease” | Co-PI, with Dr. Pim Pijnappel and Dr. G. Ruijter (main applicant).
2019 Stofwisselkracht “Exercise-based therapy for Pompe disease” €25K | PI
2018 Stofwisselkracht | MPS Co-applicant
2015-2021 (incl 2 yr extension): Center of Excellence Research Grant, Genzyme-Sanofi |Includes 15 independent research projects | Co-PI of 5 labprojects|Total amount 2.5 million Euro
2013 Prinses Beatrix Spierfonds. |“Predictive and therapeutic value of muscle stem cells for Pompe disease”|Co-PI. 4 years |€ 250,000. 
2006 Ter Meulen Fonds (Royal Netherlands Academy of Arts and Sciences | PI | Knowledge transfer grant | € 31.100,=
2005 Veni Grant NWO (Netherlands Organization for Scientific Research |PI | “Stem cells in normal and malignant muscle development“| € 200.000, =